- convert expression string tokens to single-quote-delimited
- fix bug where netclass assignments weren't getting updated after
board setup dialog
- move property manager rebuild to lazy evaluation
- improve performance with wider use of const&
- retire DRC_SELECTOR stuff
- use wxString for GUI stuff (particularly translated stuff)
- fix EqualTo() to return false instead of asserting when op types
don't match
- fix buffer overruns with fixed-size string buffers
- make expression function calls case-insensitive
- integrate expression errors into rule parser
- produce more and better error messages
- keep BOARD_ITEM ptrs const as long as possible
- fix a couple of uninitialized variables
