Invalid character issues

[weshinsley]

If a filename contains a '&', then adding the file causes invalid XML and everything goes hideously wrong the next time you start up QMP. Maybe base-64 on the filename, and strip the bad chars out of the human-readable name when writing the XML

[weshinsley]

It would be nice if this could be done in a backward-compatible way - eg, add a new tag to indicate base64, and then the absence of that tag allows non-base64 as is currently the case.