OS_CORPSE error logging tweak.

OS_CORPSE errors were being logged during hotboots because fread_obj had
no exception for the supermob hack.
Prototype zones should load after real ones.

Prototype zones were loading too far down in boot_db which caused errors
if hotboot recovery was trying to restore objects that those zones were
placing.
ImmHost memory allocation cleanup.

The ImmHost security module was incorrectly allocating std::string
objects through STRALLOC which would show up later as leftover objects
in the string hash.

ImmHost data will now also be deallocated during cleanup_memory to aid
with leak testing.