New HLT algorithms for body body trigger

I do a test run on the st_centralpro stream from Run 13116087.

As the graph showed below. I find it is need to set up a lowlimit to reject events with

very low multiplicity. In this test the events have less than 300 primary tracks is about

1.4% of total events input in to HLT.

So I add a new lowlimit of nPrimaryTracks in the body body trigger as 300 the red line,

and the low 5% cut is set as 873 blue line.