- Failed to catch all instances of modify_module when it was renamed
to setup_dependent_package.
- Refactored remaining modify_module calls.
- Also modified Python's setup_dependent_package slightly: only
creates empty site-packages directory for Python extensions now, not
for all dependents.
- Gave setup_environment and setup_dependent_environment more similar
signatures. They now allows editing the Spack env and the runtime
env for *this* package and dependents, respectively.
- modify_module renamed to setup_dependent_python_module for symmetry
with setup_dependent_environment and to avoid confusion with
environment modules.
- removed need for patching Package objects at runtime.
- adjust packages to reflect these changes.
Package repositories now look like this:
top-level-dir/
repo.yaml
packages/
libelf/
package.py
mpich/
package.py
...
This leaves room at the top level for additional metadata, source,
per-repo configs, indexes, etc., and it makes it easy to see that
something is a spack repo (just look for repo.yaml and packages).
