Fixes for unicode strings converted to ASCII.
Fixes for bytestrings that are not unicode.
Fix startswith() error if non-unicode bytestring compared against unicode prefix.
Reduce memory usage fir duplicate file hash checking.
Update ChangeLog.
Handle corrupted ZIP files.
Handle byte-strings in prefix as well as lookup filename, seen during duplicate file-hash search with song prefix as a byte-string.
Handle any ZIP decompression errors, also seen during duplicate search on invalid ZIP file.
Sanitise byte-string filenames before passing to Wx. Sanity-check song data during duplicate search.
Updates for release 0.7.5
Merge branch 'master' into gstreamer

Conflicts:
	pykdb.py
Merge pull request #17 from AThomsen/gstreamer

Bring in changes from 0.7.5