Python 3.x is patched in a way that integrates `.hy` source files into
Pythons default `importlib` machinery. In Python 2.7, a PEP-302 "importer"
and "loader" is implemented according to the standard `import` logic (via
`pkgutil` and later pure-Python `imp` package code).
In both cases, the entry-point for the loaders is through `sys.path_hooks` only.
As well, the import semantics have been updated all throughout to utilize
`importlib` and follow aspects of PEP-420. This, along with some light
patches, should allow for basic use of `runpy`, `py_compile` and `reload`.
In all cases, if a `.hy` file is shadowed by a `.py`, Hy will silently use
`.hy`.
