Added Shen_Castan_514.java.

The original plugin (that no longer works with IJ[1]), is now released
under GPL, as per Maxime Pinchon permission. The goal is to bring Shen-
Castan filtering back to IJ.
 
[1] http://imagej.nih.gov/ij/plugins/inserm514/Documentation/Shen_Castan_514/Shen_Castan_514.html
Bring Shen-Castan filtering up-to-date
 - Support for 16/32-bit images and stacks (multithreadable) 
 - Support for area ROIs
 - Preview
Rename Shen-Castan plugin to something more suitable
Update Documentation