Introduce bundle help/documentation

+ Add some meta information to the documentation
+ Create Help menu command
Arrange menu items into hierachies

Tip: Until TM2's bundle editor isn't feature-compelte, simply copy the
bundle (created with TM2) over to TM1, do the work and then copy it
back. But take care of UUIDs asf.
Add requiredCommands section

This avoids having the user explicitly set PATH or TM_DOT / TM_RAPPER.