src/mainfrm.cc,src/mainfrm.h: Pass wxString by const reference in a
couple of places where we weren't.
src/mainfrm.h: Remove unused default parameter value from
MainFrm::LoadData().
Makefile.am: (Microsoft Windows version) Include dump3d in the
installer.
NEWS: Update.
doc/cad3d.sgml: Add link to "Related Tools" section of the Survex web
site in the section about SpeloGen.