GitHub issues 78 79 81 num aff flags off by one (#82)

* Make sure all followers are free'd before freeing the character list

Otherwise, the followers structs will point to free'd memory and
the stop_follower call will attempt to dereference a free'd
characters' followers list.

* https://github.com/tbamud/tbamud/issues/79 typo

* https://github.com/tbamud/tbamud/issues/81 nullpointer crash on syntax check run

* NUM_AFF_FLAGS fix.

Now, consistently, the NUM_AFF_FLAGS is used in the same way as other
NUM_* variables. Specifically, the the number is consistent with
how others are defined - 1 above the highest in the list.

I would like to have removed the need to start from 1 instead of 0
as well, but the loading mechanism, and thus potentially a lot of
existing object files, use 0 as a marker for "no flags set", and
we can't easily fix that. So, the places we loop through the list,
we still need to make sure we're stying within the [1;NUM_AFF_FLAGS) interval.

Simultaneously, I've checked over the other flags, and it seems like
the usage is pretty consistent there.

Fixes https://github.com/tbamud/tbamud/issues/78

src/dg_event.c

@@ -151,7 +151,8 @@ long event_time(struct event *event)
 /** Frees all events from event_q. */
 void event_free_all(void)
 {
-  queue_free(event_q);
+  if (event_q != NULL)
+    queue_free(event_q);
 }
 
 /** Boolean function to tell whether an event is queued or not. Does this by