Switching from ANSI to Unicode support

for WinGetClipboard: only required changing char to wchar and using
GetClipboardData(13) for CF_UNICODETEXT

for WinSetClipboard:

changed DDESHARE to MOVEABLE (as per MSDN docs for clipboard management)
used encode for both python2 and python3, still results in a bytestring
for both versions
used wcscpy to stop copying on \0\0 instead of \0