Substituting Giac's evaluate() with direct gbasis() computation (extreme speedup in ProveDetails)

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@29838 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e
Prevent area tool from renaming the polygon

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@29839 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e