Add and use AP_GRIPPER_ENABLED

[peterbarker]

This tidies many vehicle's existing GRIPPER_ENABLED define so we also remove random library functions which are gripper-related.

[Hwurzburg]

remember any option we change we need to change the build_options.py and rebuild the features.txt, right?

[peterbarker]

remember any option we change we need to change the build_options.py and rebuild the features.txt, right?

Yep. I'll be setting a cronjob up tomorrow to update the server every hour or something.

[Hwurzburg]

dont think it needs to be every hour if its a load issue....every day or so should do if it is

[tridge]

need to work out why Pixhawk1-1M saves flash space with this change

[peterbarker]

need to work out why Pixhawk1-1M saves flash space with this change

Previously gripper was removed at the vehicle level, but the compiler was unable to remove the library functions. Now they're explicitly cut out based on the define: