Yet another sepia script, yet, this one can do a little more. This script supports two types of sepia coloring:
"Classic": According to the Sepia Toning tutorial by Eric R. Jeschke http://www.gimp.org/tutorials/Sepia_Toning/
The script desaturates the original layer and adds a sepia mask in a layer above.
The sepia mask layer has a mask which is the inverted desaturated original.
"With Hue": With hue modification of the original image.