medias: Only show play indicator if loaded

Since we are now showing a progress label, we shouldn't show the play
indicator since it will simply cover that.
Merge branch 'master' of ssh://baedersonline.de:2207/git/Corebird
filter-list-entry: Fix icon size of remove button
Remove 'notify on new followers' setting

Never worked, never will.
TweetUtils: add is_link
composing: Implement first highlighting draft

Works on a word-basis at the moment, i.e. if a section of text that is
surrounded by whitespace starts with a #, it'll be a hashtag etc.
compose: Remove debug spew
ComposeWindow: Get the highlight colors from the theme

Slightly evil, but ok.
compose: Improve mention parsing
Merge branch 'compose-hl'