Read utf8 filenames

[foolo]

Current: run wxpic åäö.jpg
filename is empty

simple test:

int main(int argc, char **argv) {
	for (int i = 1; i < argc; i++) {
		wxString s(argv[i]);
		std::cout << "s='" << s << "'" << std::endl;
	}
}

./wxpic foo output is s='foo'
./wxpic åäö output is s=''