Help: Changing the menu system to have a global menu definition

Added the help item to this global definition, and created an empty dialog for the help.
Help: Added functionality to the help menu item
Help: New way for Activities to inform the help videos they own
Help: Moving all the help menu related stuff to a new super class
Merge pull request #551 from arthurbenemann/YoutubeGuides

Youtube video guides
typo correction
Merge pull request #555 from Paku-/failsafe_fasil

typo correction