Blurred thumbnails

Extension allows to selectively blur thumbnails on Youtube videos.

# Possible configuration:
- Whitelist & blacklist
- Channel name
- Keywords in video title

# How to configure:
- Click extension icon to open options
- Click on tags to edit existing keywords
- Press enter to add new keywords
- For channels use plain names (including spaces)
- Use: ".*" as a keyword to match all patterns
- Use "Test phrase" input on bottom to check which tags will apply for given plain text