* Implement code to allow wxDC to handle coordinate conversions between
device and drawing units.
* Add build settings to enable wxGCDC for wxGraphicsContext testing.
* Remove wxAUI conditional build cruft as it is now required to build
Kicad.
* Fix scroll increment size regression to prevent jumping around the
zoom center position.
* Add find GDI+ cmake module for building on WXMSW when wxGraphicsContext
is enabled.
stambaughw