In replay.php, refactor so new g_replay_length variable controls recording length in seconds.  This isn't controllable via UI, but could be increased by code modification.  In the current implementation, multiple recordings occur in parallel, each offset by one second, so the total processing load is proportional to the recording length.
In replay.php, refactor so new g_replay_length variable controls recording
length in seconds.  This isn't controllable via UI, but could be increased by
code modification.  In the current implementation, multiple recordings occur in
parallel, each offset by one second, so the total processing load is
proportional to the recording length.

The point of this commit is to make it easier for anyone who wants to experiment
with different values, perhaps to mitigate issues like #136.  I expect the
replay implementation to change substantially for next season.

jeffpiazza/derbynet,jeffpiazza/derbynet,jeffpiazza/derbynet,jeffpiazza/derbynet,jeffpiazza/derbynet,jeffpiazza/derbynet,jeffpiazza/derbynet