* Added functionality for numerical output (CSV) format. See functions starting with "CSV" in mesh.cpp. External code hull.cpp is responsible for convex hull calculations.
- ToDo: adopt menu item "File->export cell areas" so user can choose a file name or set up periodic output of numerical data.
- ToDo: add parameters re: periodic numeric output to "<settings>" block of LeafML-file, so it becomes possible to set up numeric output interactively, then write the LeafML file and run the program in batch mode to retrieve periodic numeric output.

* Added new functionality to plugin interface. It becomes possible to define a default LeafML init file for a plugin. It is read whenever the model plugin is loaded.
- ToDo: define default LeafML files for all plugins, according to the LeafML files mentioned in the Plant Phys. tutorial.


user: Roeland Merks <merks@cwi.nl>
branch 'default'
added src/hull.cpp
added src/hull.h
changed src/TutorialCode/Tutorial0/tutorial0.pro
changed src/VirtualLeaf.cpp
changed src/VirtualLeaf.pro
changed src/build_models/auxingrowthplugin.cpp
changed src/build_models/auxingrowthplugin.h
changed src/canvas.cpp
changed src/canvas.h
changed src/mainbase.h
changed src/mesh.cpp
changed src/mesh.h
changed src/modelcatalogue.cpp
changed src/simplugin.cpp
changed src/simplugin.h
changed src/xmlwrite.cpp