Rename the path::prefresh() function to path::refresh(). Calling
convention should be to `use crate::path;` or `mod path;`, and then call
path::refresh(...), for verbosity.

Remove some commented out code, that is no longer needed after the
parser overhaul.

Add docstring for `incant_quiet_io`.

Rebuilt the LR parser (i.e. read()) from the ground up. This required
that some changes be made to recite(), in order to accomodate the new
data structures. These data structures were each split out into their
own file, in order to make working with each component a bit easier.

In addition to reworking the parts of the parser already present, some
new features were also added, such as:
  - Support for strings (' and ")
  - Support for environment variables ($)
  - Support for interpreting tild as $HOME (~)
  - Support for sub-reading and sub-reciting (`)