add python to install instructions
add pmm (power management) to gdb_x5
msp430-x5: usci-v2, Only change critical register when in SWRST.

In the latest TI x5 manual (SLAU208K) it states that certain
critical registers (and bits) should only be changed when in SWRST.

Update docs to reflect this and protect places where it makes sense.
msp430 adc12: If undefined ADC12ENC, assign from ENC.

TI's headers are inconsistent and some cpu's that have the
ADC12 hardware don't define ADC12ENC.  Rather it uses the older
unspecific ENC define.

This fix defines ADC12ENC from ENC but only for those cpus that
explicitly have the ADC12 h/w module.

Fixes tp-freeforall/prod #23
Merge branch 'tp-master' of https://github.com/tp-freeforall/prod into tp-master-andres