new statistical function in ROOT::Mathh
   landau_quantile (inverse of landau cumulative distribution) 
   translated from RANLAN
   - added also the landau_quantile_c

 - first and second momentum function of the truncated landau
   landau_xm1 landau_xm2 

- sin and cosine integral  in SpecFunc.h
  from CERNLIN (http://wwwasdoc.web.cern.ch/wwwasdoc/shortwrupsdir/c336/top.html)

  ROOT::Math::sinint(x) and ROOT::Math::cosint(x) 


- update stressMathCore with landau


git-svn-id: http://root.cern.ch/svn/root/trunk@33348 27541ba8-7e3a-0410-8455-c3a389f83636