transform skewx/skewy: fix: use tan() instead of sin()

sin() is intuitively wrong: since it can only be max 1.0,
it's not possible for the matrix to skew the object more than 45 degrees.

The tan() version is consistent with the SVG skew implementation.
macosx: build - Makefile, configure changes - added more frameworks
macosx: xproject update
macosx: by rudi
macosx: c ....
macosx: font fixes
macosx: run without crash
macosx: commented out the testing printf lines
macosx: ovals: uses CGContextAddEllipseInRect(), removed old code