Do not move sliders in move mode

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@27689 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e
Don't trigger slider dialog if another slider is clicked

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@27690 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e