scripts/mpd: fix timer start on bot load
modules/url_handler: new URL handler module
config: add url_handler module
modules/url_handler: match whole URI, change const name
lib/scripts: clean up events and URL handlers when needed
scripts/ping: fix msg -> @msg typo
lib/scripts: use URL object, not class itself, when cleaning up
modules/url_handler: add class helpers when dispatching
scripts: split title handlers into separate scripts

Title fetching is now handled by the blocks fed to the url_handler
module.

Derpibooru handler is missing for the moment. There is an unpublished
Derpibooru script which will take over that shortly.
modules/url_handler: move max from title script here
config: remove redirects from title, rename shorten_youtube to shorten_url