only adding path if it's not already added (remove duplicates).
It's cleaner this way.
git-svn-id: svn://svn.icculus.org/gtkradiant/GtkRadiant/trunk@432 8a3a26a2-13c4-0310-b231-cf6edde360e5
made Visual Studio files work in VS2005 Express
fixed a ton of warnings in VS2005 Express
fixed some compile problems on OpenSUSE 11.0
git-svn-id: svn://svn.icculus.org/gtkradiant/GtkRadiant/trunk@302 8a3a26a2-13c4-0310-b231-cf6edde360e5