geometry() sets the units for angles

- by default all angles are expressed in DEGREES, but this can be
changed to RADIANS or PERCENT
- rotate(), skew(), arc(), and oval()
- debating whether lib.geometry should also respect the setting…
background() now supports gradients & images

- same syntax as fill()
- linear gradients now accept angles in geometry() units
fixed findpath()

- it was still looking for its implementation in bezier rather than
pathmatics
- bezier() should take a curvature kwarg when called with a list of
(x,y) points
fill()-parsing cleanup