hare::module implements the module resolution algorithm used by Hare. Given that
it is run within a Hare environment (i.e. with HAREPATH et al filled in), this
module will resolve module references from their identifiers, producing a list
of the source files which are necessary, including any necessary considerations
for build tags. This interface is stable, but specific to this Hare
implementation, and may not be portable to other Hare implementations.

This module also provides access to the Hare cache via [[manifest]]s and their
related functions, but this is not considered stable, and may be changed if we
overhaul the cache format to implement better caching strategies.
