Set xterm-color for cursor element

Set xterm-color for cursor element
Prevent focus from getting lost when in vt mouse mode
Fix: cursor style not applied on init, set a class for block cursor
Make all cursors work under all conditions (focused, unfocused, blink)
Unify cursor rendering with normal rendering code
Make sure underline AND blink can be used in co-existence
Always show outlined block cursor in unfocused state