#4633 extrude refactoring

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@36898 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e
Fix for #4629

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@36899 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e
Fix for #4629

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@36900 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e
Force f(t)=(t,t) to be a line in 3D

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@36901 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e