I would like to suggest a change to the path where `tlapm` saves auxiliary files,
to the path `__tlacache__/filename.tlaps/`, for an input file
named `filename.tla`. The current path is `filename.tlaps/`.
With this change, the generated files for all the TLA+ files in a directory
would be placed under a single directory named `__tlacache__`,
so that the `*.tlaps` directories would not be listed in the working directory.
This change would imply that to load fingerprints from previous
`tlapm` versions, existing `*.tlaps` directories would need to be moved
to the `__tlacache__/` directory.
Using a common directory named `__tlacache__` is inspired by
the directory `__pycache__`  in Python 3, which stores `.pyc` files.