Implemented interlace support for GD, Imagick, and Gmagick.
Declared supported interlace types array as static
Fixed missing param and renamed interface param name

- Added missing param for array_key_exists calls
- Renamed $type to $scheme within ImageInterface::interlace
Fixed Typo
Merge pull request #196 from AnthonySterling/interlace-support

Implemented interlace support for GD, Imagick, and Gmagick.