Removing Groebner command; adding GroebnerLex, GroebnerDegRevLex, GroebnerLexDeg

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@33742 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e
Implementing CAS command Eliminate.2

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@33743 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e