Avoid overwriting loop limit and increment.


git-svn-id: https://fricas.svn.sourceforge.net/svnroot/fricas/trunk@1814 b0c55286-4f34-0410-a049-a1e7e93b0762
Expose GnuDraw.


git-svn-id: https://fricas.svn.sourceforge.net/svnroot/fricas/trunk@1815 b0c55286-4f34-0410-a049-a1e7e93b0762