tox: Update pyparsing to 2.1.4

- Split out the '==' behavior in ParserElement, now implemented
  as the ParserElement.matches() method. Using '==' for string test
  purposes will be removed in a future release.

- Expanded capabilities of runTests(). Will now accept embedded
  comments (default is Python style, leading '#' character, but
  customizable). Comments will be emitted along with the tests and
  test output. Useful during test development, to create a test string
  consisting only of test case description comments separated by
  blank lines, and then fill in the test cases. Will also highlight
  ParseFatalExceptions with "(FATAL)".

- Added a 'pyparsing_common' class containing common/helpful little
  expressions such as integer, float, identifier, etc. I used this
  class as a sort of embedded namespace, to contain these helpers
  without further adding to pyparsing's namespace bloat.

- Minor enhancement to traceParseAction decorator, to retain the
  parse action's name for the trace output.

- Added optional 'fatal' keyword arg to addCondition, to indicate that
  a condition failure should halt parsing immediately.

tox.ini

@@ -168,7 +168,7 @@ deps =
     pep8-naming==0.3.3
     pydocstyle==1.0.0
     pyflakes==1.2.3
-    pyparsing==2.1.3
+    pyparsing==2.1.4
     six==1.10.0
     sortedcontainers==1.4.4
     venusian==1.0