New graphics system + Windows support

Extensive changes since v0.1.0:

User interface changes:

• Added Windows support; download pyRouterJig.exe below
• Mac OSX app file is pyRouterJig.app.zip
• Unit system (English or metric) may be selected from Units menu.
• May select wood species through Wood menu. Changes are purely cosmetic.
• Printing now done through a print-preview window. May print to a file; the file type depends on the platform and format support.
• Underlying graphics system changed for drawing figure. Has much better window sizing response and behavior.
• Numerous bug fixes and other improvements.

0.1.0

Initial experimental release.