Fixed warnings

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@23964 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e
Removed dead code

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@23965 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e
CanvasMath: fixed bugs in previous commits, but the work is not finished

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@23966 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e