Added third reaction-diffusion protocol: Diffusion in a growing domain.

--
user: Michael Guravage <michael.guravage@cwi.nl>
branch 'default'
added data/leaves/mygrowingleaf.xml
changed src/protocols/MyDiffusionModel/mydiffusionmodel.cpp
changed src/protocols/MyDiffusionModel/mydiffusionmodel.h

Added first reaction-diffusion protocol: Diffusion dependent coloring.

--
user: Michael Guravage <michael.guravage@cwi.nl>
branch 'default'
added data/leaves/myleaf.xml
added src/protocols/MyDiffusionModel/Makefile
added src/protocols/MyDiffusionModel/mydiffusionmodel.cpp
added src/protocols/MyDiffusionModel/mydiffusionmodel.h
added src/protocols/MyDiffusionModel/mydiffusionmodel.pro
changed src/protocols/Makefile