Update to experimental r13565
Header cleanup: stop using Glib types where they aren't truly needed. Eases GThread deprecation errors.
(cppcheck and janitorial tasks:) C-style casting to C++-style casting
Cleanup for src/forward.h. (About 19 of the affected files did not require the contents forward.h at all).
compatibility patch to compile using gcc 4.6
This is the first c++ification commit from me. It handles sp-line, sp-polyline, sp-item and marks the onset of document c++ification as well. Users can check performace increase with [/usr/bin/time -v inkscape_binary_with_commandline_options].
bug 1243190: add tref element support; limited editing support thus far (patch by gbanaszk)