Fix update_mon
Converta few more uses of r_info to m_ptr->race and remove some more m_idx
De-indexify a lot more of the monster code, especially monster generation.
Nuke get_mon_num_hook, just pass it in to get_mon_num_prep() instead.
Move get_mon_num_prep() to use monster race instead of r_idx.
Deindexify more, focussing on code outside the monster/ directory.
Fix loading from savefiles after past commits.
Deindexify further
More deindexifing.
Deindexify mon-msg.c