Merge branch 'dev-stateful' into 'master'

make IStateful baseclass of IAlgTool, IAlgorithm and IService

IAlgTool, IAlgorithm and IService all declare the following pure
virtual functions:
      configure,initialize,start,stop,finalize,terminate,reinitialize
      restart and FSMState
which, presumable not by coincidence, also happens to be the
functions which IStateful declares.

This commit removes those declarations from IAlgTool, IAlgorithm
and IService, and instead makes them inherit from IStateful

Fixes GAUDI-1092

See merge request !23