names: remove unnecessary property accessors
point: clear distinction with Affine coordinates and Jacobian
curve: remove Curve.equals
Curve: move validation for Points

This is implicitly a curve based operation, and not relevant to the
Point.
Arguably a lot of the math curve context is also, but, that is not as
easy to extract yet.
Curve: remove X9ECParams and circular dependency
Merge pull request #14 from dcousens/curveapi

Partial removal of Circular parameters dependency