This allows completely avoiding the call overhead if there
are none. The downside is that the event object now has to
be a userdata with lots of metamethods.
Properly attach stack traces to errors passing the resume boundary.
Replaces coroutine.resume and coroutine.wrap with appropriately
modified versions, and adds a Lua::SafeResume function for C++.
The trick obviously is doing it without forcing DF to wait suspended.
Fortunately, lua has built-in coroutine support, so the interactive
prompt can simply yield and rely on the external loop to do the job.
To use this however the REPL had to be replaced with lua code.
- This context requires core suspend lock and asserts it in a few places.
- Special 'event' objects are introduced. They can be invoked as
functions, in which case they iterate all their fields and call
them as functions. Errors are printed and consumed.
- When a plugin is opened by the core context, events registered in
a special array are linked to it. The system is organized so as to
avoid even trying to pass the event to lua if the module isn't loaded.
Alexander Gavrilov