Fixed break in String API export

String::operator!=, String::operator==, and String::Compare functions
were all originally functions that returned BOOL.  I changed them to
return native 'bool' instead without realizing that it would break the
API.  So, sadly, I have to change them back to BOOL to prevent
incompatibilities with existing plugins.
Merge branch 'master' of https://github.com/jp9000/OBS