Merge branch 'GAUDI-1127' into 'master'

removed the need for ToolHandle<IAlgTool> specialization

Modified the implementation of BaseToolHandle so that the retrieve
method can be implemented without conflicting with the retrieve method
of ToolHandle<T> with T=IAlgTool.

This, BTW, fixes GAUDI-1127.

See CFHEP-177 and merge request !10.

See merge request !67