refs #82. Added methods and tests for navigating the history of the game.
fixed some typos
[refs #82] Added missing docstrings.
ref #82 - added a backward and forward button to the gui layout
[refs #96] Implemented slot for changing the image scanning rate
[refs #96] Implemented a menu action that opens dialog with a slider to change the camera scanning rate
[refs #96] fixed memory leaks...
[refs #114] the board detection (manual and automatic) can be cancelled with the ESC key
[refs #96] Displaying scanning rate as fps (0-40)
Merge branch 'master' into #96_adjusting_image_scanning_rate

Conflicts:
	Go_Controller/BackendWorker.hpp
	Go_Controller/main.cpp
	Go_GUI/GUI.hpp
[refs #114] Doing a board detection doesn't check the menu entries anymore
Merge remote-tracking branch 'remotes/origin/master' into #114_cancel_board_detection
[ref #79] Don't kill the app if we got some malformed data. Return instead.
Merge remote-tracking branch 'remotes/origin/master' into #82_history_navigation

Conflicts:
	Go_Backend_Unittest/backend_test.cpp
	Go_GUI/GUI.cpp
	Go_GUI/GUI.hpp
[ref #82] Implemented history navigation in the controller
refs #82 - changed font of buttons to the new font, added signals if button is pressed
closes #82 - defined signals, incommented the outcommented stuff
ref #96 - Fixed a race condition where the removed worker->scan() was still in progress when the scan timer fired for the fist time inside the worker_thread (not the same thread). This caused the camera reading to crash.
Merge pull request #130 from augmented-go/#96_adjusting_image_scanning_rate

#96 adjusting image scanning rate
Merge pull request #133 from augmented-go/#114_cancel_board_detection

#114 cancel board detection