setting the icon of Geogebra-tube

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@23415 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e
bugfix: Increment: missing from Algebra Tab

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@23417 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e