Changes from 3.4.3 to 3.4.4

Improvements

• Environment variable to control the use of embedded libraries.
  Thanks to avalentino.
• Include citation in repository.
  :issue:690. Thanks to katrinleinweber.

Bugs fixed

• Fixed import error with numexpr 2.6.5.dev0
  :issue:685. Thanks to cgohlke.
• Fixed linter warnings.
  Thanks to avalentino.
• Fixed for re.split() is version detection.
  :issue:687. Thanks to mingwandroid.
• Fixed test failures with Python 2.7 and NumPy 1.14.3
  :issue:688 & :issue:689. Thanks to oleksandr-pavlyk.