Consider consolidating the core load into fewer files

[Mercerenies]

At the time of writing, there are 14 separate files (excluding latitude.lats and the mode-specific files such as repl.lats, etc) in the core load process, totaling 2417 lines of code. This is an average of 172 lines per file.

It remains to be fully profiled, but it is possible that the number of core files may be slowing down the load process somewhat, so consider moving the 14 files into a new collection of fewer files.