Add features and general improvements to YouTube Subscriptions page.
Features:
- Allows creating categories and grouping channels in them.
- Makes video thumbnails display a bit larger, like in the home page.
- Filters out less relevant videos (by views / time since upload) of the same channel if that channel spams a lot of videos in a short period of time.
Known bugs:
- If the categories menu doesn't appear you may need to refresh the page.
How to create a category:
- You can update the lists at the beginning of the user script with the name of each channel and category.
- The same channel is allowed to be in multiple categories.
- Channels not assigned to any category will automatically appear in "Rest".
- The special category "All" will display all channels, ignoring categories.
