The Steinhart-Hart equation was changed in code long ago to the
B-parameter equation. Rename references to it and the interface
accordingly. The `s-h` command is now `b-p`.
The reason the name "B-Parameter" equation was chosen over
"Beta-Parameter" was due to its easier searchability.
Current limit pins are driven by PWM inputs to the MAX1968 driver, but
this is an implementation detail, and should not be exposed in the form
of the command interface. Rename "pwm" to "output" in all instances.
See M-Labs/thermostat#62 (comment).
