Some last fine-tuning
- File dialogs start from appropriate data directories
- XML files contain right values for datadir
- Reordered parameter dialog
- Added new "make perl" heading to the makefile
- Corrected segfault for batch mode

user: Roeland Merks <roeland.merks@cwi.nl>
branch 'default'
changed data/leaves/auxin_growth.xml
changed data/leaves/meinhardt_init.xml
changed data/leaves/tutorial1_init.xml
changed data/leaves/tutorial2_init.xml
changed data/leaves/tutorial3_init.xml
changed data/leaves/tutorial4_init.xml
changed data/leaves/tutorial5_init.xml
changed src/Makefile
changed src/VirtualLeaf.cpp
changed src/VirtualLeafpar.tmpl
changed src/canvas.cpp
changed src/canvas.h
changed src/mesh.cpp
changed src/mesh.h
changed src/modelcatalogue.cpp
changed src/modelcatalogue.h
changed src/parameter.cpp
changed src/parameter.h
changed src/pardialog.cpp
changed src/pardialog.h