Merge pull request jenssegers#59 from artyuum/patch-1

Now prioritizing Imagick over GD

Merge pull request jenssegers#38 from bogdanstoik/patch-1

Fix setting of default implementation

Merge pull request jenssegers#34 from jenssegers/imagick

Imagick

Merge pull request jenssegers#24 from klermonte/master

Fix hexadecimal to decimal conversion for negative  hashes

Require php ext in composer file

Update readme with decimal mode

Fix image source in readme

Testing Docker support on Travis

Improve gmp hamming distance

Trying to speed up hamming distance calculation