Added Blocks folder + some Block dummys

Signed-off-by: web32 <maximilian.soellner@stf-group.de>
Added Block.cs

Signed-off-by: web32 <maximilian.soellner@stf-group.de>
Modified GUI.cs to work with MainMenu

Signed-off-by: web32 <maximilian.soellner@stf-group.de>
Merge remote-tracking branch 'origin/web32'