Submerge DPV Thumb Trigger

A thumb trigger for Submerge DPV units, with the design intent to better enable mutli-tap control systems.

Ergonomics could be improved I think, so consider it a version 1.0

UPDATE: I dived this and wasn't a big fan. The travel distance to engage multi-taps is still too great. I don't recommend this trigger though will leave it up here for inspiration. I will make a revision at some point hopefully.