Added Save and Load function

The history is now able to load and save a game from to disk
Class is now serializable
Enabled menu points for loading/save
Added file dialogs to the form
Added new Game loaded event

The debug view will now show the game loaded message
Add function for load and save

The form is able to show a filedialog to create or load a savegame
Bug fixes and new features

images are loaded only once
fixed issue with position calculation
added function to load or save a game
Bug fixes and new checks

Fixed a bug in the king in check movment calculation
Added the check for moves that could bring the king in check