1) make sure we get the default netclass when we want it
2) escape for HTML (particularly important for "<invalid>", but also
for reporting user rule names, netclass names, etc.)
Be more intelligent about sorting lib tree items. (Footprint
entries, for instance, come out of an already-sorted list.)
Don't recreate menus twice when laoding Footprint Editor.
More pervasive use of WX_FILENAME to avoid expensive calls to
wxFileName::SplitPath() and string concatenation.
For POSIX kernels do all the work on the file-system side so we
don't have to keep converting back and forth between encodings.
Jeff Young