[giac] remove '' from eg '3*5' from ifactor(15) + tidying

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@25837 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e
[giac] add poly1[] to the Giac parser

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@25838 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e
4.9.142.0

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@25839 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e