Everything is now based off of default font pixel size

Also adding a constant for the font size in SensorComponent.

- cancel support
- mag rotation images
- set board rotation before cal
- set compass rotation after mag cal

Also changed to pull specific small parameters set after cal instead of
full refresh. This way, the red/green indicators update much more
quickly.

Passing parameters QVariantMap across C++ boundary was causing crashes
in Qt due to Qml array bugs. Referencing same Fact* across Qml boundary
in multiple QQuickWidgets caused jScript GC to crash.