Merge from vendor branch TNF:

Merge from vendor branch TNF:
Importing ruby-chunky_png version 1.2.0.  It is required by newer version
of www/ruby-compass.

= Chunky PNG

This library can read and write PNG files. It is written in pure Ruby for
maximum portability. Let me rephrase: it does NOT require RMagick or any other
memory leaking image library.

== Features
* Decodes any image that the PNG standard allows. This includes all standard
  color modes, all bit depths and all transparency, interlacing and
  filtering options.
* Encodes images supports all color modes (true color, grayscale and indexed)
  and transparency for all these color modes. The best color mode will be
  chosen automatically, based on the amount of used colors.
* R/W access to the image's pixels.
* R/W access to all image metadata that is stored in chunks.
* Memory efficient (uses a Fixnum, i.e. 4 or 8 bytes of memory per pixel,
  depending on the hardware)
* Reasonably fast for Ruby standards, by only using integer math and a highly
  optimized saving routine.
* Interoperability with RMagick if you really have to.

Also, have a look at OilyPNG at http://github.com/wvanbergen/oily_png.
OilyPNG is a mixin module that implements some of the ChunkyPNG algorithms
in C, which provides a massive speed boost to encoding and decoding.