Revert "Revert "Add ability to under- and overvolt.""

This reverts commit a57a935e92515ecc48845eef6a1477de1423a8fe.
Revert "FEATURE: Ezekeel's LiveOC and Custom Voltage"

This reverts commit 8af28b9230d8348b45903a365d77d6e8fb452e18.