Peter M. Groen / oletools

Another recent pull request changed the outcome of 2 tests for one
sample. However, those results do not appear on my system or the github
integrated unittest systems. Maybe detection is dependent on system
encoding?

Need to investigate, exclude sample for now.

(1) Cannot open a temp file for writing from 2 python processes
    simultaneously
(2) Need proper environment setup for Popen (thanks to metatoaster's
    reply on stackoverflow https://stackoverflow.com/a/72845540/4405656)
(3) Need different os-separator, so replace hard-coded '/' with
    os.path.join or os.sep
(4) Minor cleanup of imports & whitespace in test_issue_*.py

There are still 2 tests that should be adapted to Windows, but those are
lower-prio in my eyes.

Also, unittest run on my windows VM creates many resource warnings due to
non-closed file descriptors. Should address that some (future) day.

With the creation of ftguess oleid has been changed a lot, the output
of its .check() method is very different. Instead of just adapting the
existing unittests, I re-created the complete test, trying to make it
easier to change/extend in the future.

Checks output on all data in tests/test-data dir