Ticket #3748: fixing real-time changing of formula sizes with style bars

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@30995 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e
#3882 ChiSqueareCell better to have as inner class

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@30996 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e
[giac] #3971, make diff(cos(x)=1) return -sin(x)=0

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@30997 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e