`TGeometry.rotate`: Pass degrees to `TPoint.rotate`

[jonnyarnold]

There was a bug where TGeometry.rotate didn't pass the degrees parameter to TPoint.rotate, meaning that calls to TGeometry.rotate (and TDocument.rotate) only ever rotated the polygon by 180 degrees.

Potential fix for #133?

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[athewsey]

Thanks for proposing! This seems like a sensible & small fix to me... Any chance you could add a unit test? It seems like the current ones in test_trp2.py only look at TPoint.rotate which is probably why this fell through the cracks.