Error handling for touch, cleaned up in other projects

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@26828 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e
Ticket #3461: big gaps in square-root signs fixed

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@26830 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e
Error handling improvements

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@26832 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e