Sinden Lightgun - trigger fixes

Remix of https://www.thingiverse.com/thing:5210938 by [slikk66](https://www.thingiverse.com/slikk66)
which is a remix of https://www.thingiverse.com/thing:4972138 by [kevman323](https://www.thingiverse.com/kevman323)
which is a remix of https://www.thingiverse.com/thing:4927415 by [hexxed](https://www.thingiverse.com/hexxed)

Mine may not be better than the original(s) but it's made to match my preferences.
I did many tries before I get to the right balance for me and although there are many things that could be improved, now that I'm happy with it I'm stopping, time to play!