[ODE] AutoDisable

[gl]

> It seems that all we need is the decision on angular movement threshold.
> Would it be ok if it just was a fixed (per-body) value?

Sure, but it would be good if you could pass the global values into a call
somewhere, rather than having to modify the source to change them.  I have
my own auto-disabling code, and much depends on how aggressive you want to
be, your ERP/CFM values etc.
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gl