Make various preparations for upcoming features

A lot of this is random WIP from a while back, at least a month ago, and
is being committed now to get it out of the way so that other patches
can be brought in and integrated against it without causing headaches.

Also rolled into this commit is a way to distinguish plugin_unload from
exiting the game. This is required for another soon-to-be-integrated
feature to avoid crashing on exit, and could in theory also be used to
speed up unloading on exit in future. While we're at it, this also
avoids the need to linearly scan through the plugin list to do the
old branch unloading fix, because we can.

Rough summary of the other smaller stuff I can remember doing:
- Rework bitbuf a bit
- Add some cryptographic nonsense in ac.c (not final at all)
- Introduce the first couple of "chunklets" libraries as a sort-of
  subproject of this one
- Tidy up random small bits and bobs
- Add source for a small keypair generation tool
- Rework democustom to be very marginally more useful

1 files changed, 2 insertions, 5 deletions

diff --git a/src/democustom.h b/src/democustom.h
index a0a28b8..7f0c25e 100644
--- a/src/democustom.h
+++ b/src/democustom.h
@@ -17,12 +17,9 @@
 #ifndef INC_DEMOCUSTOM_H
 #define INC_DEMOCUSTOM_H
 
-/* maximum length of a custom demo message, in bytes */
-#define DEMOCUSTOM_MSG_MAX 253
-
 /*
- * Write a block of up to DEMOWRITER_MSG_MAX bytes into the currently recording
- * demo - NOT bounds checked, caller MUST ensure length is okay!
+ * Writes a custom demo message, automatically splitting into multiple demo
+ * packets if too long. Assumes a demo is currently being recorded.
  */
 void democustom_write(const void *buf, int len);