StartConversationEntry: Cancel on empty screen name
UserListsWidget: Don't create lists with empty names
account-list-entry: Remove margin-top

We don't need that anymore since the SettingsDialog isn't using tabs.
main-window: Put avatar_image and compose button into a GtkBox

Needed for the 2 separators in the titlebar to not look different
because of the ".header-bar > GtkBox > .separator.vertical" rule in
Adwaita.
Merge branch 'master' into compose-completion
ProfilePage: more g_message -> g_debug transitions
ProfilePage: Load older tweets when scrolled down

Related to #136
ComposeTweetWindow: Update completion on cursor change
ComposeTweetWindow: Hide the completion window on focus loss
ComposeTweetWindow: Fix completion with empty word
Completion: Correctly hide window on space
ComposeTweetWindow: Move word detection into its own function

We will also need it in another place
ComposeTweetWindow: Fix completion in newline

This previously did not work because the way we detected the 'current
word'(i.e. the word the cursor is in) did not take newline texts into
consideration
UserCompletion: Ignore @ prefix
ComposeTweetWindow: attach compose window to text view
Merge branch 'compose-completion'
compose-window: Add tooltip to image button
pot update
README: Fix dependencies
Utils: Catch exception in write_pixbuf_async