Inlining Ref Functions

[dsimcha]

== Quote from grauzone (none at example.net)'s article
> Of course, this doesn't have to do with DMD's optimizer. That said, if
> you want heavy optimization, you rather should look at LDC or GDC.

In general I agree.  There are higher priorities than improving DMD's optimization
back end.  This is a special case, though, because:

1.  Innocent looking code can turn into a significant performance bottleneck.
2.  I would guess it's a very low hanging piece of fruit, since ref is just
syntactic sugar for a pointer and DMD already can inline functions with pointer
parameters.