Username filtering

[Xithrius]

Filters can now be done on not just messages, but usernames too. Originally the Filters structure only supported filtering of messages.

For username filtering, if you don't want bots, you can add something such as this to your config:

[filters]
[filters.username]
filters = [
    ".*bot.*"
]
enabled = true

Filters will now be searched in the following order (with message and username filters not relying on another to function):

1. Configuration file at both filter.message.filters and filters.username.filters
2. The file specified at filters.message.path and filters.username.path. Each filter must be separated by a newline if you want multiple.
3. The contents of the file located at the configuration folder base (such as ~/.config/twt/), then both message_filters.txt and username_filters.txt. Each filter must be separated by a newline, just like the previous step.