Update platform definitions to latest SDK
Remove script used to grep Cocoa headers for grammar symbols

This is no longer used, instead we used a libclang-based approach.
Include ‘source.c.platform#functions’ instead of redeclaring them
Remove legacy completion command (using dialog 1.x)
Don’t show “Completion: Inside @selector” in the bundle menu

This is consistent with the other two completion commands.
Remove legacy support files for documentation lookups
Update completion index (using 10.10 SDK)