mythzmserver: fix the debug output telling us which mmap files we opened
MythZoneMinder: finish the support for ZoneMinder >= 0.26.0

All combinations of capture palette and target colour space should now be
supported. This also moves all the processing to mythzmserver and always
passes RGB24 to the plugin.

Note: bumps the protocol version so both mythzmserver and the plugin need to
be updated.
Merge remote-tracking branch 'upstream/master'