aheckmann/gm — pull request #93 by danmilon (2012-11-07 19:19:25+00:00)
Title: Add support for thumbnail

Currently the helper `.thumb` first performs a `.size`, computes crop dimensions, and then crops and resizes the image.

I want to generate thumbnails but tried to avoid this two-pass method. I bumped into a [superuser question](http://superuser.com/questions/275476/square-thumbnails-with-imagemagick-convert) which uses the `-thumbnail` option, but this is not available in gm.

This pull requests extends args with support for thumbnail, includes a simple test, and an example. I reckon thumbnail might conflict with thumb in a naming sense, but its the official name.