0.4.2

This version adds some minor transforms. Additionally, a major terminology cleanup has been done. The thingamajigs that measure physical signals are called sensors. The sensor outputs are modified by transforms and then sent to the SK server using an SKOutput. The whole physical clump of wires and bits of PCB is called an "ESP device".

GPS compass functionality has been sufficiently fixed to work. The device also no longer forgets its Wifi configuration if it isn't able to connect to the server. Oops.