Enforce PEP8 naming conventions for things like variables, methods,
classes, etc.

See the table here:

https://pypi.org/project/pep8-naming/

...for error codes emitted, in case some should be added as
exceptions in the flake8 configuration files.

* py-pytest: Added dependency on py-setuptools-scm, as well as py-setuptools, to prevent the build from silently installing its own copy of setuptools-scm

* py-pytest: Dependency on setuptools-scm only needs to be 'build'

py-snuggs: Added depends_on py-parsing. The build uses setuptools, which would otherwise silently try to install pyparsing itself, presumably into the python home dir (obviously not ideal). (#8748)

py-pkgconfig: Made nose dependency type=build,test instead of just type=test, to prevent setuptools from silently installing its own copy of nose (#8749)

* openmpi: add c++ exceptions cfg option variant

* address review comments

Replace regex-based target detection for Makefiles with a preliminary "make -q"
to check if a target exists. This does not work for NetBSD make; additional work
is required to detect if NetBSD make is present and to use a regex in that case.
The affected makefile target checks are only performed when the "--test" flag is
added to a "spack install" invocation.

* py-pyqi: new package

* py-pyqi: cleanup

* The xlf_seacas.patch fails on the latest trilinos develop branch so confine it up to version 12.12.1.

* Fixing likely mistak in seacas patch version range.

Fixes #8036

Before this PR Package.installed was returning True if the spec prefix
existed, without checking the DB. This is wrong for external packages,
whose prefix exists before being registered into the DB. Now the property
checks for both the prefix and a DB entry.

Spack provides a number of classes based on commonly-used build systems
that users can extend when writing packages; the classes provide functionality
to perform the actions relevant to the build system (e.g. running "configure" for
an Autotools-based package). This adds documentation for classes supporting the
following build systems:

* Makefile
* Autotools
* CMake
* QMake
* SCons
* Waf

This includes build systems for managing extensions of the following packages:

* Perl
* Python
* R
* Octave

This also adds documentation on implementing packages that use a custom build
system (e.g. Perl/CMake).

Spack also provides extendable classes which aggregate functionality for related
sets of packages, e.g. those using CUDA. Documentation is added for
CudaPackage.

* fftw: version bump

* fftw: add gcc-8 conflict for v3.3.7

* Add fix for bug causing build failure when hdf5 enabled

* Added correct hdf5 dependency to typhonio

* r: add memory profiling variant

* r: change memory_profiling to underscores

- The setup-env.sh script currently makes two calls to spack, but it
  should only need to make one.

- Add a fast-path shell setup routine in `main.py` to allow the shell
  setup to happen in a single, fast call that doesn't load more than it
  needs to.

- This simplifies setup code, as it has to eval what Spack prints

- TODO: consider eventually making the whole setup script the output of a
  spack command

* aspera-cli: a new package.

* flak8.

This allows building MPI applications on top of charm/AMPI without
to specify another backend.

* Charm: more info about build targets

* fix whitespace

* Charm: provide MPI
* add mpicc wrappers
* clarify MPI comment

* update help of `clean --all` to include `-p`
* remove old orphaned `.pyc` removal
* restrict removal or orphaned pyc files to `lib/spack` and `var/spack`

* Unset F90 in mvapich2 when using intel compilers.

* Fixing typo.

* Unset F90 and F90FLAGS for mvapich2 at all times.

* Adding comment.

Prevent this error:

metis_graph_part.c:301:7: error: non-void function 'METIS_PartGraphVKway' should return a value
      [-Wreturn-type]

* 	modified:   package.py

* 	deleted:    var/spack/repos/builtin/packages/py-numexpr/numexpr-2.6.5.tar.gz

* 	new file:   var/spack/repos/builtin/packages/py-backcall/package.py

* Update package.py

* Update package.py

* Update package.py

* Update package.py

* flang: add support for llvm-6

* flang: review changes

* pgmath: make flake8 happy

- Clean up error messages for when a lock can't be created, or when an
  exclusive (write) lock can't be taken on a file.

- Add a number of subclasses of LockError to distinguish timeouts from
  permission issues.

- Add an explicit check to prevent the user from taking a write lock on a
  read-only file.
  - We had a check for this for when we try to *upgrade* a lock on an RO
    file, but not for an initial write lock attempt.

- Add more tests for different lock permission scenarios.

- write locks previously wrote information about the lock holder (host
  and pid), and read locks woudl read this in.

- This is really only for debugging, so only enable it then

- add some tests that target debug info, and improve multiproc lock test
  output

- llnl.util.lock tests are now independent of Spack

- multiproc doesn't depend on Spack
- llnl.util.lock test uses it, but shouldn't use parts of Spack.