Implementing variable permutations for Singular (ProveDetails)

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@28210 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e
unused imports in webapache

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@28211 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e