Change simplicity analysis: previously all inline coded combinations

Change simplicity analysis: previously all inline coded combinations
were treated as simple, now there are some (e.g. generic arithmetic)
which are not.  There is still a problem relating to type checking
which could cause problems: if a type or range check fails in an
otherwise simple inlined combination, the exception handling is not
simple.  This should be fixed without making the entire combination
non-simple.