Move numberOfDaughters() and daughter(size_t) outside class declaration

Break virtual inline. This will make numberOfDaughters() and
daughter(size_t) symbols with GLOBAL binding. Before it was in LOCAL
binding thus breaking compilation of `testCommonToolsUtil' from
CommonTools/Utils. Needed for GCC 4.9.0.

Signed-off-by: David Abdurachmanov <David.Abdurachmanov@cern.ch>
Merge pull request #2477 from davidlt/break-virtual-inline

Move numberOfDaughters() and daughter(size_t) outside class declaration