Transform and transformRGBA are using the inverse of the given transform

[GoogleCodeExporter]

It seems that this entire package uses *inverse* transformations from the usual 
convention.

This is borne out by examination of the Transform functions, which transform 
from the destination to the source to look up pixels.

In addition, each of the Rotate, Translate, etc. functions generates an inverse 
matrix (for example, Translate puts -x and -y in the translation terms; 
Rotation produces at clockwise rotation by documentation, while the matrix it 
provides usually produces a ccw rotation).

If this is intentional it needs to be clearly documented - providing your own 
affine transform doesn't work as expected - you have to invert it first.

To fix this we'd need to add an Invert() function and call it before the 
transformations.  I'm happy to provide a patch if this is the correct route.

Original issue reported on code.google.com by Paul.A.L...@gmail.com on 12 Jan 2012 at 7:13