`./build decl` now builds TS declarations for everything exported by
`sim/`. Unfortunately, the built TS declarations still refer to global
types, so some things still have `any` type, but it's much better than
nothing.
A lot of Net functions returned Promises that would not reliably
resolve/reject if a Net request failed. This fixes it so they should
now all reliably reject on request failure.
(Yes, this fixes the ladder issues and memory leak in Main.)
Previously, ending a read stream was `stream.push(null)`, and ending a
write stream was `stream.end()`. This was often confusing, and so now,
these are consistently `stream.pushEnd()` and `stream.writeEnd()`.
This refactor already found a bug in which `stream.end()` was used
where `stream.push(null)` should have been.
Also in this refactor: By default, `pushError` ends the stream. You can
pass `true` as the second parameter if the error is recoverable (the
stream shouldn't end).
