cherrypicked from my workbench
loaddata and dump scripts for Virtuoso isql-vt added
Overview for the Pol. Sys. and related classes
Added sdsage.py that allows using SD in Sage
Docu: http://symbolicdata.org/wiki/PolynomialSystems.Sage
refactored GeoProofSchemes cherrypicked from hgg workbench
Merge branch 'rc-1' of github.com:hg-graebe/symbolicdata into workbench
fixed variable list syntax