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`.

mapeditor.cpp

@@ -2128,7 +2128,7 @@ namespace mapeditor {
     }
 #endif    
 
-  auto hooks = addHook(clearmemory, 0, [] () {
+  auto hooks = addHook(hooks_clearmemory, 0, [] () {
     if(mapeditor::painttype == 4) 
       mapeditor::painttype = 0, mapeditor::paintwhat = 0,
       mapeditor::paintwhat_str = "clear monster";