[ODE] more c++, auto-enabling

[Russ Smith]

> Whoops, duh, my bad.  I guess it's reasonable for slow-step not to
> have user-configurable auto-enabling, 

to keep the internals simple, the principle is that when a live
(enabled) thing touches a dead (disabled) thing, the dead thing becomes
live .. not having this behavior would raise all sorts of tricky
questions, like what happens to a live body when it is connected by a
joint to a dead body. if the dead body behaves as though it was a live
body fixed in space then this would require a lot more work than just
setting and checking a few flags (not saying it can't be done, just that
it's not trivial).

russ.

-- 
Russell Smith
http://www.q12.org