[game] Process more than one action per frame

[modawan]

We used to execute up to 1 action per frame. With a high dt
multiplier, a single frame takes ~100ms (virtual time, 8x dt). For a
busy queue of multiple actions (script continuations, for example), it
is possible that processing actions one by one will take much longer
than for a queue of a single action.

With DelayCommand actions, it is crucial that they execute in the same
relative order, even when pushed to different queues. With the "1
action per frame" limitation, it is possible that commands in a busy
queue can be delayed for so long, they effectively execute
out-of-order relative to a command in a single action queue, for
example.

This happens with k_pebn_pophawk and k_pebo_carthtlk when running
with 8x dt multiplier:

• k_pebn_pophawk spawns Carth with a 0.5s delay (module queue).
• k_pebo_carthtlk starts a dialogue with 1.0s delay (trigger queue).

The module queue contains other delayed commands, so it takes a few
frames to process them. The trigger queue only has 1 action, so it can
execute before the module queue actually gets to execute the spawn
command.