scp-fs2open
Add multi support to external SEXPs
This adds (mostly) automatic multi support to the external SEXP system. This will record the parameter values that were evaluated for the master and automatically send them to the client via the standard SEXP packet system.
For SEXPs where the behavior does not differ between master and client there needs to be no special handling of the multi case in the SEXP action code.
FYI, this moves set-motion-debris-override to the external engine SEXP and makes it compatible with multi with this new system.
Yes, if a SEXP chooses to do all the multi stuff itself then disableMulti is what is needed. In that case the SEXP action is still called on the client so it can all be be handled in the same function.
