add credits [ci skip]
add ruler space UI
doxygen
Merge branch 'master' into TaCredits

Conflicts:
	app/Joker/JokerWindow.cpp
	app/Joker/JokerWindow.h
	app/Joker/JokerWindow.ui
	app/Joker/en_US.ts
	app/Joker/fr_FR.ts
update translation
Merge pull request #181 from Phonations/TaCredits

add credits and space ui fix #153 fix #144