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`.

racing.cpp

@@ -835,7 +835,7 @@ heptspin sview;
 #if CAP_COMMANDLINE
 auto hook = 
   addHook(hooks_args, 100, readArgs)
-+ addHook(clearmemory, 0, []() {
++ addHook(hooks_clearmemory, 0, []() {
     track_ready = false;
     track.clear();
     rti.clear();