GUI: Abstract method added to GamePanelBase. Implementation of methods in classes that extends GamePanelBase.
Merge branch 'master' into gui_test

Conflicts:
	src/client/controllers/HostBtnController.java
	src/client/controllers/JoinBtnController.java
	src/client/controllers/MyBombFielsBtnController.java
	src/client/views/ClassicGamePanel.java
	src/client/views/MainWindow.java
	src/client/views/NewGameDialog.java
	src/client/views/component/PlayerGameBoardPanel.java
Mixed:
- HostBtnController: Hardcoded GameDifficulty (quick, brutal fix so nullptrexc wont show up).
- ClassicGamePanel: Change setGameBoard to addPlayer - generalization of main GamePanels method.
- MainWindow: Size and location of components in "NewGameWindow" changed. Now its not resizable.