CMakeLists.txt: Remove unused compiler options
Add DoubleTapButton

Which is an ordinary GtkButton which needs to be activated twice in
order to actually invoke the action associated with it.
Remove follower.png/svg

which is nowhere used anymore
Utils: Make show_error_object more robust

It now also works if the json stirng is malformed(in which case the
alternative will be shown).
Also, if the josn data does not contain an 'errors' array, but just an
'errors' string, we simply show that.
TweetUtils: Use show_error_object more often
Use a DoubleTapButton as retweet_button
MainWindow: Correctly call on_leave on pages
Merge branch 'master'
Merge branch 'master' into double-tap

Conflicts:
	src/util/Utils.vala
README: Fix retweet shortcut
TweetListEntry: Set correct link handler of rt_label

... woops.
Utils: Remove unneeded catch clause
ImageLabel: Fix the label's size

See issue #64
Add a TweetListBox widget

... we us to unify the placeholder stuff which now also has a way to
indicate that simply no results have been found.
Relevant for issue #57
ProfilePage: Use a TweetListBox

So we can easily indicate missing tweets if the user has not yet tweeted
anything.
Utils: Use $XDG_CONFIG_HOME in user_file

See issue #65
tweet-list-entry: Dont show the conversation_image no show_all
Remove obsolete files
Corebird.vala: code style
MainWindow: Clean up the headerbar mess