use intersecting circle's omega points & perspective

* arc is drawn from the perspective of the intersecting circle's center
  + provided by computeIntersectAngles()
  + cairo_arc() draws clockwise
* computeOmegaPoints() provides intersect angles from unit circle's center
new Point constructor for std::complex<double> & exercise it

* provide a Point constructor for accepting std::complex<double>
* exercise new Point constructor with an example
test animation capabilities w/ GtkDrawingArea

cairoPoincare.h
* move Point class from testPoincareDisk.cpp
* make drawPoint(), drawLine() and drawUnitCircle() accept cairo_t*

testAnimation.cpp
* animate expanding/contracting {5,1} convex- & {5,2} star-polygons

testPoincareDisk.cpp
* move Point class to cairoPoincare.h
points number to constant, full +/- unit cycle, disable debug code
move rotation adjustment out as variable, make it animatable
use machine epsilon when drawing & skip animation frame at r ~= 0
Update README.md