The use of printf, wxLogDebug, and std::err/std::out causes excessive
debugging output which makes finding specific debugging messages more
difficult than it needs to be.
There is still some debugging output in test code that really needs to
be moved into a unit test.
Add debugging output section to the coding policy regarding debugging
output.
The attached patch makes the following changes to the IDF
tool 'dxf2idf':
1. DXF units are now correctly scaled to mm
2. Polylines are now supported
3. LWPolylines are now supported