TweetInfoPage: Mark the location label no-show-all

*Someone* forgot that.
ComposeWindow: Activate image upload again
ComposeTweetWindow: Formatting
Utils: Add show_error_object

Shows an error object received from Twitter in an error dialog.
ComposeTweetWindow: Use better error handling

also, get rid of the Gtk.Stock usages
ComposeWindow: Change the file chooser's positive button to 'chooser'

It's not like it saves anything.
ComposeTweetWindow: Update media count on media remove
TweetListEntry: Also pass the application instance to the compose win
ProfilePage: Load user tweets
Merge branch 'master' into new-profiles