Consistently name every hookset with prefix hooks_. NFC.

I'm sure this causes massive merge-conflicts in the non-public code,
but I think it'd be a good idea, if only to avoid confusion between
e.g. `clearMemory` and the-variable-formerly-known-as `clearmemory`.

blizzard.cpp

@@ -251,7 +251,7 @@ EX void drawArrowTraps() {
     }
   }
 
-auto ccm_blizzard = addHook(clearmemory, 0, [] () {
+auto ccm_blizzard = addHook(hooks_clearmemory, 0, [] () {
   arrowtraps.clear();
   blizzardcells.clear();
   bcells.clear();