[DGD] Callout hack

[Shentino]

Speaking of callouts...I'm trying to hack DGD so that millisecond
callouts can have durations of longer than 60.0 seconds.

I've noticed that the millisecond encoding is as follows:

8 bits (value 1) that say it's a millisecond callout
8 bits for the seconds,
and 16 bits for the milliseconds.

Would I be in for a major overhaul if I rearranged the bits as follows:
2 bits for the callout type
20 bits for the seconds
10 bits (1024 > 1000) for the milliseconds

I've found the encode and decode routines, but there may be other
pieces of code out there in the source in other files I may miss, and
I wanted to check with anyone in the know before I go mucking with the
source.

For the kind of work I'm doing, 60.0 seconds just ain't enough, and I
don't like rounding to the nearest second and skipping queues.  I
could use millitime, but that isn't immune to statedumps.