PMT/CPU fixes

* Fixes #14 - adds PMT idle mode
* Reduces OCP polling frequency

See merge request !4

Hotfix #12

Fix #12 

See merge request !3

Support reading and writing TCS threshold. Added checkbox to short CE/RE for 2-electrode mode. Finishes #6.

These packages are still technically required, but they do not
install nicely via pip (so there is no advantage to including them)
and including them causes errors when installing this package on
Linux.