- fix in AsymptoticCalculator the formulae for the two-sided test statistics for both observed and expected p values
- improve search for upper/lower limit in InverterResult
  add also a flag to indicate in the InverterResult if it comes from using a two sided test statistic.  
 This is needed to use the right formula for the asymptotic case. 

- Add also possibility to skip and to not draw the points where there is a failing fit or any other error

- Add in Profile likelihood possibility to query if the test statistic is one or two sided


git-svn-id: http://root.cern.ch/svn/root/trunk@44126 27541ba8-7e3a-0410-8455-c3a389f83636