Remove undefined functions superseded by Strutil.

Strutil::utf8_to_utf16 and Strutil::utf16_to_utf8 replaced path_to_windows_native and
path_from_windows_native respectively.
Fix MSVC cast warnings.
Do not rely on the shell to expand wildcards for the oiiotool test.

This fixes the test for Windows, where unlike bash the shell does not expand wildards.
CHANGES and bump version for 1.2.1 release