Refactored "Rules"

Moved some methods which were identical into "rulehelper.cpp" and
"rulehelper.h".
Moved folder "rules" into folder "player"
Merge branch 'master' into assembly_ai

Conflicts:
	harbour-reversi.pro
	src/player/staticruleaiplayer.cpp
	src/player/staticruleaiplayer.h
	src/translation/reversi-core_de.ts
	src/translation/reversi-core_en.ts