An option to read extra properties (comments or metadata) while reading with ImageMagick.
Do nothing by default if no extra property is asked for.
Added an option to simply output the existing extra properties. Non existing properties give a warning. Added some documentation and tests.
Merge remote-tracking branch 'upstream/master'
Merge remote-tracking branch 'upstream/master'
Merge pull request #209 from romainFr/master

An option to access extra properties while reading with ImageMagick