Export(pstricks,pgf,asymptote):many fix for the piecewise defined functions and their integral

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@37841 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e
Make sure Help works for Custom Tools part 1

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@37842 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e
Make sure Help works for Custom Tools part 2

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@37843 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e