Improved the implementation of FindKerberos5.cmake module. Fixes  ROOT-5486
Silence current XCode warnings in a minimally intrusive way.
Add a message when data size is empty
Revert "Silence current XCode warnings in a minimally intrusive way.".

This reverts commit 3593116c0c58eb483238b381cef44a45cc8c255a.
New version of 3593116c0 - clarify by leaving it as comment.
Improved version of 3593116c0: Silence current XCode warnings
Fix JIRA-ROOT-5488. The matrices used by the Td and Tm PDF text operators (used to position and rotate text) cannot be concatenate with the current transformation matrix. This produced wrong slanted text for greek letters when the text angle was not zero. Now the operator "cm" is used instead of Td and Tm, allowing to concatenate the text transformation  matrix with the matrix used slant the text.
fix a typo
  o RooAbsArg

    - Allow clone() to take null-ptr as argument (implies same object name)
      Save on CPU performance in string manipulation when cloning object trees.

    - Make setExpensiveObjectCache() virtual so that it can be overloaded in RooRealVar
      [ fixes JIRA-5502 ]

    - Make copy ctor accept null-ptr as name argument

    - In redirectServers() change algorithm to prevent proxy self-reference to not longer
      use temporary sets - this saves enormously in the complexity of tree cloning operations
      as redirectServers() is N^2 operation in tree cloning
  o RooAbsCollection

    - In RooAbsCollection::remove() by name, use comparison of
      unique TNamed* pointers instead of string comparison
      to match names.
  o RooAbsOptTestStatistic

    - Trim verbosity of reporting on cached or cache-and-tracked nodes: if there are
      more than 20, just report the total number

    - Remove some obsolete code that was already commented out
  o RooAbsPdf

    - Cosmetics
  o RooAbsTestStatistic

    - Add code that identifies binned probability models of the form created by HistFactory
      (a RooRealSum of RooHistFuncs, optionally multiplied with one or more subsidiary models)
      and allow optionally calculate these as a fully binned likelihood calculation.
      To trigger this calculation each identified model must additional carry a Boolean
      attribute "BinnedLikelihood". This code is introduced as a transition to proper
      modeling of binned likelihoods and probabilities in RooFit 4.0

    - Add flag to create() virtual copy ctor to indicate binned likelihood calculation mode
  o RooArgProxy

    - Implement protection against cyclical reference to object owner here
      [ moved from RooAbsArg::redirectServers() ]
  o RooChi2Var, RooDataWeightedAverage, RooXYChi2Var

    - Follow interface change in create()
  o RooHashTable

    - Don't use nptr comparison in bucket lists as that causes unwanted recursion
  o RooHistFunc

    - Add workspaceStreamerHook() and modify Streamer() to forcibly load embbeded RooDataHist object
      as embedded dataset in the workspace. This makes the embedded histogram visible to the user
      and automatically take are of expensive object cache redirections of these objects
  o RooNLLVar

    - Add code that reintreprets pdfs marked as 'binned likelihood' as yield
      vectors (divided by bin-width) for a Poisson product model and evaluates the log-L in the corresponding
      approach. In this approach no explicit normalization of the 'binned pdf'
      needs to be calculated, saving time and logistics.
  o RooStats::HistFactory::FlexibleInterpVar

    - Performance optimization: replace chained if() with a switch,
      replace .at() with [] to avoid repeated bounds-checking

    - Remove largs swaths of commented out obsolete code
  o RooStats::HistFactory::PiecewiseInterpolation

    - Performance optimization: replace chained if() with a switch,
      replace .at() with [] to avoid repeated bounds-checking

    - Remove largs swaths of commented out obsolete code

    - Performance tuning of icode=4 algorithm: avoid unnecessary
      multiplications by contracting these in precalculated constants,
      calculate higher powers of x in terms of previously calculated
      powers, improve internal if() chain to converge faster
      Add comment to NOT touch this code --> this segment of code
      dominates HistFactory CPU performance in many use cases.