Update license

Introduce the new get-involved wiki page with information about how to
contribute to GammaRay.
Set a valid URL.
Use the official license code.
Fedora 19 or higher needs an extra package for pod2man.
Split out -devel package.
Enable KDE4 plugins and put them into a separate package.
Work around FindKDE4Internal messing up CMAKE_INSTALL_RPATH.

This did put invalid relative paths into RPATH.
Add KDE4 rpath fix patch.
Work around graphviz not being detected on Fedora 19.

Also, fix the Fedora package naming.
Enable the VTK plugin where possible.
Remove duplicated help from CMakeLists.txt

The help string for GAMMARAY_UNKNOWN_CXX_MANGLED_NAMES is already passed
to option(...)
Minor: These files come from kdiff3
Minor: Fix header
Merge remote-tracking branch 'origin/1.3'