* Deleted kicad_exceptions, because it required the big #include <wx/wx.h> and
    that was slowing down compiling.  Moved that stuff back into richio.h where
    it came from.
  * Enhanced IO_ERROR to format an errorText.
  * Added THROW_IO_ERROR() and THROW_PARSE_ERROR() macros to capture the
    the call site of the thrower.  If you have problems compiling, it is probably
    due to the definition of __LOC__ in richio.h.  Some compilers may not support
    __func__ in C++ yet.  Find a macro that identifies your compiler, and we can
    work out something in the #define of __LOC__.