cppcheck: performance + variable type

Update 2Geom to pull in integer rectangle class

* src/2geom/isnan.h, src/libcola/cola.cpp, src/style.cpp, src/seltrans.cpp, src/libcola/gradient_projection.cpp, src/libvpsc/generate-constraints.cpp, src/libnr/nr-types.cpp, src/libnr/nr-point-fns-test.cpp, src/isnan.h, src/libnr/nr-point-fns.cpp, src/libnr/in-svg-plane-test.cpp, src/doxygen-main.cpp, src/display/nr-filter-composite.cpp, src/display/nr-filter-merge.cpp, src/display/nr-filter-gaussian.cpp, src/display/bezier-utils.cpp, src/Makefile_insert, src/eraser-context.cpp, src/dyna-draw-context.cpp, src/tweak-context.cpp, src/sp-namedview.cpp, src/libnr/in-svg-plane-test.h, src/libnr/nr-point-fns-test.h, src/mod360-test.h, src/CMakeLists.txt, src/2geom/linear.h: Properly fix the conflicting isnan.h problem: 1) Update src/2geom/isnan.h to match newest Inkscape src/isnana.h (Also commited this change to lib2geom project repository) 2) Remove Inkscape's src/isnan.h 3) Update all files to include src/2geom/isnan.h instead of src/isnan.h

merge gsoc2008_johan_path2geom into trunk

committed patch 1710682 by jfaith - in src/libcola/cola.cpp, isnan is used and not the cross-platform definition isNaN defined in isnan.h => replaced isnan by isNaN and included isnan.h - add math.h include in src/libcola/gradient_projection.cpp This was necessary because libcola does not compile for OS X 10.3.9

commited Solaris 2.8 / gcc-3.2.3 fixes

- Connectors with end-markers now constrained to point downwards in graph layout - vpsc namespace added to libvpsc

Previously graph layout was done using the Kamada-Kawai layout algorithm implemented in Boost. I am replacing this with a custom implementation of a constrained stress-majorization algorithm. The stress-majorization algorithm is more robust and has better convergence characteristics than Kamada-Kawai, and also simple constraints can be placed on node position (for example, to enforce downward-pointing edges, non-overlap constraints, or cluster constraints). Another big advantage is that we no longer need Boost. I've tested the basic functionality, but I have yet to properly handle disconnected graphs or to properly scale the resulting layout. This commit also includes significant refactoring... the quadratic program solver - libvpsc (Variable Placement with Separation Constraints) has been moved to src/libvpsc and the actual graph layout algorithm is in libcola.