Introduce SharedTemporaryFile (bis)

[guyer]

Create a temporary file shared by all MPI ranks

(Previous attempt #767 got broken)

[wd15]

Add a test maybe? Also add to linter?

[wd15]

Works for me and documentation looks good

[tkphd]

LGTM. Nice docstrings! 👍

[guyer]

black trashes the formatting recommended buy PEP8 and Donald-Frigging-Knuth, and then pylint complains about it.

E.g, black --target-version py27 --fast fipy/tools/sharedtempfile.py changes

def SharedTemporaryFile(mode='w+b', buffering=-1, encoding=None,
                        newline=None, suffix="", prefix=template,
                        dir=None, delete=True, communicator=parallelComm):

to

def SharedTemporaryFile(
    mode="w+b",
    buffering=-1,
    encoding=None,
    newline=None,
    suffix="",
    prefix=template,
    dir=None,
    delete=True,
    communicator=parallelComm,
):

which leads to pylint spewing:

fipy/tools/sharedtempfile.py:23:0: C0330: Wrong hanging indentation before block (add 4 spaces).
        mode="w+b",
        ^   | (bad-continuation)
fipy/tools/sharedtempfile.py:24:0: C0330: Wrong hanging indentation before block (add 4 spaces).
        buffering=-1,
        ^   | (bad-continuation)
fipy/tools/sharedtempfile.py:25:0: C0330: Wrong hanging indentation before block (add 4 spaces).
        encoding=None,
        ^   | (bad-continuation)
fipy/tools/sharedtempfile.py:26:0: C0330: Wrong hanging indentation before block (add 4 spaces).
        newline=None,
        ^   | (bad-continuation)
fipy/tools/sharedtempfile.py:27:0: C0330: Wrong hanging indentation before block (add 4 spaces).
        suffix="",
        ^   | (bad-continuation)
fipy/tools/sharedtempfile.py:28:0: C0330: Wrong hanging indentation before block (add 4 spaces).
        prefix=template,
        ^   | (bad-continuation)
fipy/tools/sharedtempfile.py:29:0: C0330: Wrong hanging indentation before block (add 4 spaces).
        dir=None,
        ^   | (bad-continuation)
fipy/tools/sharedtempfile.py:30:0: C0330: Wrong hanging indentation before block (add 4 spaces).
        delete=True,
        ^   | (bad-continuation)
fipy/tools/sharedtempfile.py:31:0: C0330: Wrong hanging indentation before block (add 4 spaces).
        communicator=parallelComm,
        ^   | (bad-continuation)

The hell with linting.

[guyer]

@wd15 @tkphd I've added a test and added (and then deleted) linting. Please recheck.