Add runtime.KeepAlive calls to prevent GC finalizers (refs gographics…

…#120)

Add runtime.KeepAlive calls to prevent GC finalizers (refs gographics…

…#120)

* 126 Added AffineMatrix API

Merge branch '106_ScaleKernelInfo'

ImageMagick 7.x Support

Update README to include info about ImageMagick 7.x support

Imagemagick >= 6.8.9-10

Imagemagick < 6.8.9-10

Fixes memory management w/ PixelIterator (im >= 6.8.9)