Change default wmname to LG3D

Based on #558 (and lots of other issues in the past, including previous
complaints about pycharm not working out of the box), we should just default to
something that actually works here. This should have essentially no effect for
anyone but users of java apps, who will experience them working correctly :)
Added Net widget that displays Up and Down speed.

Closes #559
Squashed cAllow spaces in ThermalSensors sensor tag

Closes #556
Closes #554