Blender Git Loki

python/utf8 compatibility fixes. (as discussed on the mailing list)

- user input gets non utf8 chars stripped all text input other then file paths.

- python has the same limitations, it will raise an error on non utf8 strings except for paths use unicode escape literals so its possible to deal with saving to these file paths from python.

- new string functions
BLI_utf8_invalid_byte(str, len) returns the first invalid utf8 byte or -1 on on success.
BLI_utf8_invalid_strip(str, len) strips non utf-8 chars.