[mat-dev] Removal of hachoir

Hello everyone,

I just issued a commit to completely remove hachoir from MAT, since this
library isn't really maintained anymore. This is a first step toward
python3 support.

Images are now completely handled by exiftool, since the main python
imaging library (PIL) doesn't play very well with metadata and
non-standard files. Also, audio files are managed with mutagen.

If you're a package maintainer, please update the dependencies to
reflect that.

o/