Widget idea/request: vehicle side-view pitch indicator

[Williangalvani]

I was recently watching some videos of comercial ROVs on youtube, and one of them had a side-view widgeteof the vehicle (that rotated) to indicate the current pitch. I found that to be very intuitive, and I think we should do something similar.

Bonus points for having the vehicle image be configurable or come from blueos.

related to #440