Remove Flickr downloader

Our API key has been broken for months and there is no free option to get a new one.
Remove this downloader because we cannot reasonably support it given these circumstances.

Closes varietywalls#702.
Closes varietywalls#812.

Author: jlu5

CONTRIBUTING.md

@@ -38,10 +38,6 @@ Every new image source to be added to Variety should meet several criteria:
   wallpapers. The general policy is that we prefer quality over both quantity and searchability /
   customization.
 
-Suggestions for adding specific Flickr photographers' feeds as default sources are also welcome, as
-long as their images meet the license and quality criteria above (the other two are met
-by default with Flickr)
-
 ## Code style
 
 We use Black and isort, using line length of 100 symbols.
@@ -86,8 +82,8 @@ To install glade on Ubuntu:
 sudo apt install glade
 ```
 
-If you just run it and try to open one of the .ui files in `data/ui`, 
-it would give you an error. 
+If you just run it and try to open one of the .ui files in `data/ui`,
+it would give you an error.
 Here is how to run it successfully:
 ```
 GLADE_CATALOG_SEARCH_PATH=data/ui/ glade data/ui/PreferencesVarietyDialog.ui

README.md

@@ -5,7 +5,7 @@
 Variety is a wallpaper manager for Linux systems. It supports out-of-the-box most Linux desktop environments, and can be configured to work
 on more esoteric ones.
 
-It can use local images or automatically download wallpapers from Flickr, Wallhaven, Unsplash, Bing, Reddit and other online sources,
+It can use local images or automatically download wallpapers from Wallhaven, Unsplash, Bing, Reddit and other online sources,
 allows you to rotate them on a regular interval, and provides easy ways to separate the great images from the junk.
 Variety can also display wise and funny quotations or a nice digital clock on the desktop.
 

serverside/variety_server_options.json

@@ -1,8 +1,4 @@
 {
-  "flickr": {
-    "min_fill_queue_interval": 1200,
-    "min_download_interval": 1200
-  },
   "wallbase": {
     "min_fill_queue_interval": 1800,
     "min_download_interval": 1800

setup.py

@@ -22,7 +22,7 @@
     packages=find_packages(exclude=['tests']),
     long_description="""
 Variety is a wallpaper manager for Linux systems. It supports numerous desktops
-and wallpaper sources, including local files and online services: Flickr,
+and wallpaper sources, including local files and online services:
 Wallhaven, Unsplash, and more.
 
 Where supported, Variety sits as a tray icon to allow easy pausing and resuming.
@@ -38,4 +38,4 @@
         'variety': ['data/**', 'locale/**'],
     },
     include_package_data=True,
-)
+)