Fix a memory leak in assignment operator. The functions objects in the list of functions were not deleted

Add unused routines in order to suppress the error message:

include/RooTreeData.h:33:10: error: private field '_tree' is not used [-Werror,-Wunused-private-field]
  TTree *_tree ;           // TTree holding the data points
         ^

When creating mergers, the code iterates over all slaves to figure out how
many workers should be assigned to each merger. This is usually fine,
unless not all are active. In that situation it creates mergers that wait
forever (or almost forever) for workers which will never connect, which
obviously screws up the job. The fix changes the merger creation to iterate
over fActiveSlaves instead of fSlaves.

[From B.Butler, M.Swiatlowski]

TString is missing a newline; will refactor printing of delims (to be done by pcaller).

(cherry picked from commit 1ef652a8)

We use the git2cl found here: http://repo.or.cz/w/git2cl.git.
Two issues were fixed:
   - strip correctly out merge commits
   - strip out git-svn-id's

All the pictures used by docbook to render the math formulae have been removed.

Same solution as in standalone cling.

While llvm needs to ignore it (it's an external project) we have all in one git repo.