This commit makes spectator mode and slave mode in netplay always stay
ahead of the input, thereby avoiding rewinds, which is sort of the
point. This also changes catch-up detection to be a bit less eager, so
that they hopefully don't flap between stalling for server input and
catching up with that input.
This used to be a configuration option because spectator mode and "net"
mode were incompatible. When the ability to switch between player and
spectator was added, the configuration option was removed, since it was
no longer a mode toggle. This re-adds it, mainly so that I can use it to
implement regression tests.
This patch transfers core_reset across netplay. Resets effectively
worked before thanks to check_frames, but this makes resets work even
without check_frames, and in particular should allow resets to force
sync in savestateless cores, bringing them one step closer to actually
being usable by non-experts.
Previously, the host would time out waiting for the guest to enter a
password, as the timeout was not conditionalized on whether the guest
was actually playing. This fixes that.
The SRAM transfer in netplay handshake now uses autosave_lock and
autosave_unlock. Will possibly fix a hang/crash bug on Android with
netplay and autosave conflicting.
Previously, if two clients were connected to the same server and one of
them was ahead of the server, the only way to rectify that situation was
for the client to get so far ahead that it stalled, as the server could
only catch up with an ahead client if all clients were ahead. That's
unrealistic. This gives the server the alternate option of demanding
that a client stall. This keeps things nicely in line even with >2
players.
