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 #115] Calculate the differences between the setup in the last update call and the current board setup, can be used to display the missing or faulty stones on the board if a move was illegal
[refs #96] fixed memory leaks...
[refs #114] the board detection (manual and automatic) can be cancelled with the ESC key
Revert "Merge pull request #108 from augmented-go/Go_Scanner"

This reverts commit 7bac7d63b22904e5af69e673d29bb1b3ac07c366, reversing
changes made to ae87d25505f12871bcda91b2bc35efc752a2a9e9.

cause of the scanner bug i could not debug
refs 115 - Implemented a red circle that is shown around the stones that differs from the real board. So all differences between real board an virtual board are shown on the virtual board.
closes #115 - Implemented the red circle around the differing stones
(commited first without # sorry)
refs #115 added/edit some comments
[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
refs #115 - Quick fix for the crash if go_game is null
[ref #115] There aren't differences between the real and internal board if there was a valid move!
[fixes #137] When there are still stones to capture, it now displays a different error message.

Added the "Make sure your board matches the virtual one."-part because when you make any other changes to the board besides capturing stones, the backend still returns UpadateResult::ToCapture.
Merge remote-tracking branch 'remotes/origin/master' into #114_cancel_board_detection