Support for 12mm - 12.5mm power switches

[jon-harper]

This would be nice. Requested by Level Fun Games via Twitter.

• Would require a new base version, but there is only one front base version ATM.
• Would also add more universal base versions...
• Maybe done as front panel option? Offer a version of the base without a switch?
• Gives the option of a reset button next to it (which won't fit in the base).

Targeting release after 0.9.9.

[jon-harper]

I've added a version of this to unstable: https://github.com/jon-harper/OmniBox/commit/1496ec4ccc7531d10752d829810a0926ec6c3f15

I've done a fit test with a 12mm switch and have updated the 0.9.10 BOM. Closing for now.