* import the code from GLee into our repository (a single source and header file), and replace all use of the check_extension function by use of GLee functions
* Remove function stencil_one_pass and replace all calls to it with `if (GLEE_EXT_stencil_two_side && GLEE_EXT_stencil_wrap)`
Patch from ticket 8 by Buginator (with some minor additions by me)
git-svn-id: svn+ssh://svn.gna.org/svn/warzone/trunk@4687 4a71c877-e1ca-e34f-864e-861f7616d084