I7 : DRHOOK instrumentation

All IFS routines shall have DRHOOK calls as first and last statement, unless referenced explicitly in exceptions list.

The string argument to these calls must give the name of subroutine. In the case of a contained subroutine, the string should be constructed from the name of the parent routine and the contained routine, separated with a percent symbol (%).

The exceptions list should only contain routines that are called in time-critical / tight contexts, where DRHOOK overhead would not be acceptable.