manually mingw-w64 installations should now work as well, as long they are in the PATH variable
check for some more errors during ./configure which may cause wclang not to function properly
cache cmdargs.appendexe too with WCLANG_WRITE_*_CACHE
can now save C and CXX invocation cache in different files (WCLANG_WRITE_CXX_CACHE=1, WCLANG_LOAD_CC_CACHE=FILE)