Drawj2d 0.6.3 released

This release adds a convenient method to draw rectangles and adds more examples to the function reference.

Changes:
- new commands rod, fillrod
- new commands movepolar, linepolar
- new command geom.polar
- commands label and texlabel enhanced: new parameter C (center)
- command point: abbreviation pt, p depreciated
- pdf metadata: creator set to Drawj2d
- documentation: more examples