[hm] Control probe is no longer TEMP_PIT, now first non-disabled probe

Note that a probe reading "Off" isn't disabled, only probes with their
type set to DISABLED count as disabled.
[hm] Optimize code of control probe to store control probe rather than calculate it all the time

~50 bytes smaller but uses 2 more bytes RAM
[hm] Fix not selecting correct control probe on boot, PID status shows control probe now
[hm] Don't reset PID[I] when changing the I constant, it really serves no purpose but to mess up the control algorithm

-- Thanks to R-Burk for pointint this out