First feeble systematic tests.
Added simple debug trace utility.
Added Pt() class for points, and touch-tests.
Re-write of Dim.__init__() and fromStr()
WIP: propagate Pt() through primitives.
Added tests for SquarePad
Added spec for fromKwargs() classmethod.
Reworked everything around Pt() class.
Merge branches 'points' and 'master'