Tweaked project files to delete/regenerate parameter and pardialog files only if perl is installed. Added new top-level Makefiles. See ChangeLogs for more details.

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user: Michael Guravage <michael.guravage@cwi.nl>
branch 'default'
added src/Makefile
added src/build_models/Makefile
added src/parameter.cpp
added src/parameter.h
added src/pardialog.cpp
added src/pardialog.h
changed .hgignore
changed src/ChangeLog
changed src/VirtualLeaf.pro
changed src/build_models/ChangeLog
changed src/libplugin.pro