Add feature to Browse commons via app (#1716)

* Search activity, image search fragment added

* Removed explore icon xml

* Updated Javadocs for search Activity and Navigation Base Activity

* SearchImageItem class updated

* Javadocs added for search activity

* removed redundant code and added javadocs for search image modules

* Javadocs added for updateImageList  method

* Rename featuredImage to explore

* Fixed null query issue

* changed cisibility to gone in case of successful Fetch

* Consolidate the networking libraries - drop volley in favor of OkHttp

* Extracted a few networking related items into a new Dagger module and finished the process of mocking the main component for tests.

* Refactoring to extract GpsCategoryModel and ensure single-responsibility-principle is maintained in CategoryApi.

* fixed featured image back bug

* Localisation updates from https://translatewiki.net.

* Javadocs added

* Add option to set image as wallpaper (#1535)

* Add option to set image as wallpaper

* Added java docs

* Toast message on setting the wallpaper successfully

* Localisation updates from https://translatewiki.net.

* SearchHistory Fragment added

* Search History Item added

* Content Provider, RecentSearchesDao added

* Database version changed to 7 and added methods for find, save ,..

* Delete icon deleted

* Reverted changes in gradle files

* Reverted changes in gradle files 2

* Optimized Improts

* reverted refractor for container name

* Refactored packagename, changed name to query in POJO class.

* Updated lastUsed to lastSearched

* Javadocs updated

* Check if user has been in search page for 5 seconds if yes then save it to history

* If else indentation updated

* added import in test

* edittext replaced with Searchview

* RxSearchview added

* Added support for API 21+

* Snackbar removed on success

* Improved code

* Pagination added

* Removed unnecessary toast

* Comment added in method

* Support for landscape mode added

* Fixed screen rotation issue on Explore and Search activity

* Clear focus added

* Delete all function added in Content Provider and called from fragment

* Scrollbar Recyclerview added

* Share Icon changed to 32 dp and back button added in explore, search activity.

* Removed unnecessary code

* Wrote and run tests for Recent Searches
 (creating db, migrating from versions, deletion, finding,..

* Category Search Fragment added

* Adapter factory added

* Renderer added

* Improvements

* Viewpager adapter added

* Updated XML

* Improvements in category card design

* tabs colors changed

* renamed images to media

* Java docs improved

* Javadoc added for setTabs

* JavaDoc for ViewPagerAdapter added

* Refreshed listview after delete

* Added mediaContainer

* Fixed ghost issue in image search fragment

* Ghost issue for categories fixed

* Removed Calling API call onback press

* Category Details activity added

* Menu added in category details activity

* back button added

* back button bugs

* Improvements in category images fragment

* JavaDoc added for some methods

* trimming added, Tab layout hided, recent searches refreshed

* SubCategory list fragment added, API added to extract subCategory Details

* API params updated to get more precise results

* Javadocs added for MWAPI method

* Pagination removed

* Fix API for fetching images inside category

* Parent category API added

* Fix #1704

* Fix #1704 corrected

* Fix #1702

* Fix #1702 and #1704

* added try catch statements

* Optimimzed imports

* loops replaced with Functions

* Javadocs for various methods added

* Fix java docs for Dao

* Javadocs for various methods added

* Fix java docs for Dao

* More javadocs added for explore Feature

* Javadocs added

* Javadocs added

* Improvements in indentation (#1739)

app/src/main/res/values/strings.xml

@@ -1,5 +1,7 @@
 <?xml version="1.0" encoding="utf-8"?>
 <resources>
+  <string name="title_activity_explore">Explore</string>
+  <string name="navigation_item_explore">Explore</string>
   <string name="preference_category_appearance">Appearance</string>
   <string name="preference_category_general">General</string>
   <string name="preference_category_feedback">Feedback</string>
@@ -83,6 +85,7 @@
   <string name="title_activity_settings">Settings</string>
   <string name="title_activity_signup">Sign Up</string>
   <string name="title_activity_featured_images">Featured Images</string>
+  <string name="title_activity_category_details">Category</string>
   <string name="menu_about">About</string>
   <string name="about_license">The Wikimedia Commons app is an open-source app created and maintained by grantees and volunteers of the Wikimedia community. The Wikimedia Foundation is not involved in the creation, development, or maintenance of the app. </string>
   <string name="trademarked_name" translatable="false">Wikimedia Commons</string>
@@ -196,6 +199,8 @@
   <string name="background_image">Background Image</string>
   <string name="mediaimage_failed">Media Image Failed</string>
   <string name="no_image_found">No Image Found</string>
+  <string name="no_subcategory_found">No subcategories found</string>
+  <string name="no_parentcategory_found">No parent categories found</string>
   <string name="upload_image">Upload Image</string>
   <string name="welcome_image_mount_zao">Mount Zao</string>
   <string name="welcome_image_llamas">Llamas</string>
@@ -286,11 +291,20 @@
     <string name="error_fetching_nearby_places">Error fetching nearby places.</string>
     <string name="appwidget_img">Pic of the Day</string>
     <string name="app_widget_heading">Pic of the Day</string>
+  <string name="menu_search_button">Search</string>
+  <string name="search_commons">Search Commons</string>
+  <string name="images_not_found">No Images matching %1$s found</string>
+  <string name="title_activity_search">Search</string>
+  <string name="search_recent_header">Recent searches:</string>
+  <string name="provider_searches">Recently searched queries</string>
+  <string name="error_loading_categories">Error occurred while loading categories.</string>
+  <string name="error_loading_subcategories">Error occurred while loading subcategories.</string>
 
   <string name="successful_wikidata_edit">Image successfully added to %1$s on Wikidata!</string>
   <string name="wikidata_edit_failure">Failed to update corresponding Wikidata entity!</string>
   <string name="menu_set_wallpaper">Set wallpaper</string>
   <string name="wallpaper_set_successfully">Wallpaper set successfully!</string>
-
+  <string name="delete_recent_searches_dialog">Are you sure you want to clear your search history?</string>
+  <string name="search_history_deleted">Search history deleted</string>
   <string name="user_not_logged_in">Login session expired, please log in again.</string>
 </resources>