- Solver ported.

Solution to problem that midpoint is internally a focus follows...
The code
Solving a mistake in calculations of sage sheet, now it works.
Working implementation of InternalAlignmentConstraints...
Major bug fix: One constraint per DoF in Internal Alignment Equations
code clean up
All equations for InternalAlignment are linear (non_squared)
Bug fix: Element widget support for Ellipse
Fix: Tangency icon position