Add missing forward declaration
Add proper (de)initialization to abstract shell surface
Remove unused forward declaration
Adjust initialization of ws_shell_surface
Adjust initialization of xdg_surface
Move methods for setting the position to the abstract surface
Fix recognicion of repeated events

Turns out the value is not `1` for repeated events, but `2`. This means
that:
 * my previous approach broke because I was comparing the value directly
 * instead of looking things up in an array, I can just look at the
   value and use _this_ as a base for recognicion of repeated events
Add missing reset of the hotkeys' state
Merge pull request #539 from neithernut/mod-compositor-consolidate_shell_surfaces

Mod compositor consolidate shell surfaces
Merge pull request #537 from neithernut/fix-hotkeys-keypress_evaluation

Fix hotkey evaluation
Add flag test for deserializing multiple transactions
Move initialization of deserialize_state object to own function
Add reinitialization of internal state object