[ODE] more c++, auto-enabling

[Matthew D. Hancher]

> no: the processIslands() function does auto-enabling for the slow-step
> function (all processed bodies get their body-disabled flag removed).

Whoops, duh, my bad.  I guess it's reasonable for slow-step not to
have user-configurable auto-enabling, since it takes a conservative
approach.  Fair enough, I've put the SF1 suffix back on the end of the
C++ auto-enable wrappers in that patch.  :)

mdh