Fix ( workaround only) crash (Windows only) when a quasi modal frame (like footprint viewer) was called from a dialog (like the component properties dialog in schematic editor).
Very minor other fixes.
* Use version of DateAndTime that returns a wxString and delete the
version that takes a char* as it is no longer required.
* Merge StrNumICmp() and StrLenNumICmp() into StrLenNumCmp() to create a
single function for comparing strings with integers and remove a lot
of duplicate code.
* Remove unused strupper from string.cpp.
* Use wxArrayString for sorting the EDA_LIST_DIALOG contents.