* Update URL parsing regexes and tests

* Get rid of no longer used README

* Merge py-udunits and py-cf-units

* netcdf -> netcdf-c

* setup_environment -> setup_*_environment

* Fix doc tests

* Few last minute fixes

* Simplify prefix removal copypasta

In spack#13411, `setup_environment` was split into `setup_build_environment`
and `setup_run_environment`, with the `spack_env` and `run_env`
arguments being changed to `env`.  Somehow the flux package was the only
one to not have its `spack_env` references in the function changed to
`env`.

In spack#13411, `setup_environment` was split into `setup_build_environment`
and `setup_run_environment`, with the `spack_env` and `run_env`
arguments being changed to `env`.  Somehow the flux package was the only
one to not have its `spack_env` references in the function changed to
`env`.

In spack#13411, `setup_environment` was split into `setup_build_environment`
and `setup_run_environment`, with the `spack_env` and `run_env`
arguments being changed to `env`.  Somehow the flux package was the only
one to not have its `spack_env` references in the function changed to
`env`.

* flux: add `url_for_version` to support their C4 repo model

Flux uses a fork of ZeroMQ's Collective Code Construction Contract
(https://github.com/flux-framework/rfc/blob/master/spec_1.adoc).
This model requires a repository fork for every stable release that has
patch releases.  For example, 0.8.0 and 0.9.0 are both tags within the
main repository, but 0.8.1 and 0.9.5 would be releases on the v0.8 and
v0.9 forks, respectively.

* flux: add latest versions

* flux: remove master from `when=@0.X:,master` statements

Now that #1983 has been merged, master > 0.X.0.

* flux-core: remove extraneous `99` patch version in `when` range

Replace `when=@:0.11.99` with `when=@:0.11` since the intention is to
include all patch versions of `0.11`.

* flux-core: fix `setup_build_environment` after changes in #13411

In #13411, `setup_environment` was split into `setup_build_environment`
and `setup_run_environment`, with the `spack_env` and `run_env`
arguments being changed to `env`.  Somehow the flux package was the only
one to not have its `spack_env` references in the function changed to
`env`.

* flux: add runtime environment variables that Flux checks

with older versions of Flux (i.e, 0.0:0.13), FLUX_CONNECTOR_PATH must be
set by spack to prevent failures in certain
scenarios (flux-framework/flux-core#2456).

the flux binary also sets some other environment variables, which can be
listed by running `flux -v start`.  I added a few of those just to be
sure that the Spack-installed paths are used, rather than
system-installed ones.

* flux: add optional testing dependencies to maximize test coverage

Install optional dependencies to ensure that only spack-installed
software is detected and that all tests are run when `spack install
--test` is used.

Flux's test suite will test for the existance of valgrind, jq, and any
MPI installation.  If it detects them (even if they are system-installed
and outside the spack environment), it will run optional tests against
them.  I noticed on my machine that the valgrind tests were running
against the system-install valgrind.

* flux-sched: switch to new `setup_run_environment` API