Add the SeleniumBase Universal Translator API

[mdmintz]

Add the SeleniumBase Universal Translator API

SeleniumBase supports the following 10 languages:

• English
• Chinese / 中文
• Dutch / Nederlands
• French / Français
• Italian / Italiano
• Japanese / 日本語
• Korean / 한국어
• Portuguese / Português
• Russian / Русский
• Spanish / Español

Multi-language tests are run with pytest like any other test. Every test method has a one-to-one mapping to every other supported language. Example:
self.open(URL) = self.开启网址(URL)

You can use SeleniumBase to translate any test from one language to another by using the console scripts interface:

seleniumbase translate

* Usage:
seleniumbase translate [SB_FILE].py [LANGUAGE] [ACTION]

* Languages:
``--en`` / ``--English``  |  ``--zh`` / ``--Chinese``
``--nl`` / ``--Dutch``    |  ``--fr`` / ``--French``
``--it`` / ``--Italian``  |  ``--ja`` / ``--Japanese``
``--ko`` / ``--Korean``   |  ``--pt`` / ``--Portuguese``
``--ru`` / ``--Russian``  |  ``--es`` / ``--Spanish``

* Actions:
``-p`` / ``--print``  (Print translation output to the screen)
``-o`` / ``--overwrite``  (Overwrite the file being translated)
``-c`` / ``--copy``  (Copy the translation to a new ``.py`` file)

* Examples:
Translate test_1.py into Chinese and only print the output:
>>> seleniumbase translate test_1.py --zh  -p
Translate test_2.py into Portuguese and overwrite the file:
>>> seleniumbase translate test_2.py --pt  -o
Translate test_3.py into Dutch and make a copy of the file:
>>> seleniumbase translate test_3.py --nl  -c

* Output:
Translates a SeleniumBase Python file into the language
specified. Method calls and ``import`` lines get swapped.
Both a language and an action must be specified.
The ``-p`` action can be paired with one other action.
When running with ``-c`` (or ``--copy``) the new file name
will be the orginal name appended with an underscore
plus the 2-letter language code of the new language.
(Example: Translating ``test_1.py`` into Japanese with
``-c`` will create a new file called ``test_1_ja.py``.)

---

Also included in this Release are the following updates/changes:

• Allow multithreaded browser sessions to be reused when specified
• Update the pytest dependency version to 5.4.2
• Improve error-handling when using headless mode on Linux
• Add methods for controlling Local Storage and Session Storage:

self.set_local_storage_item(key, value)
self.get_local_storage_item(key)
self.remove_local_storage_item(key)
self.clear_local_storage()
self.get_local_storage_keys()
self.get_local_storage_items()
self.set_session_storage_item(key, value)
self.get_session_storage_item(key)
self.remove_session_storage_item(key)
self.clear_session_storage()
self.get_session_storage_keys()
self.get_session_storage_items()