caching: check for windows path separator
caching: check for windows path separator

Simplify and add error checking

ace20022/libbluray,Azzuro/libbluray,ace20022/libbluray,Azzuro/libbluray,Azzuro/libbluray,tourettes/libbluray,tourettes/libbluray,ShiftMediaProject/libbluray,tourettes/libbluray,tourettes/libbluray,ace20022/libbluray,ace20022/libbluray,ShiftMediaProject/libbluray,Azzuro/libbluray,ShiftMediaProject/libbluray,ShiftMediaProject/libbluray