[Python3] Several changes to migrate the code to python3 (part 3)

[ngosang]

This PR contains the commits from #4985 and #4980. After other PRs are merged this PR will be rebased.
This PR is the 3rd in [Python3] series and the first one with python3 support.
Main discussion: #4975

You wanna help?

• Test with python2. Everything should work as usual.
• Test with python3. Main features are working. Report all problems you found (trace + python version)
• Request other people to test!

Instructions to test

• git clone https://github.com/ngosang/Medusa.git
• cd Medusa
• git pull and git checkout feature/py3_2
• edit config.ini and change debug = 1
• python -V or python2 -V or python3 -V
• python start.py or python2 start.py or python3 start.py
• Try to enable/configure all features in the webui

Known bugs

• python2/python3 unicode in sqlite3 => Bug in history tab / develop #5139

Disclaimer:

I'm testing careful with both python2 and python3 interpreters. With python2 you should expect the same functionally than development branch. Python3 is a long term goal, first versions won't be functional or even won't run.

[p0psicles]

@medariox 1d347d8 and ec25183

Tested deluge-web. Couldn't get deluged to work in docker.

[labrys]

@medariox @p0psicles @duramato and any others:

There have been some major changes to nzbtomedia in nightly, with more to come. It now fully supports Python 3. If any of you have the time to test the changes in nightly and report any issues it would be greatly appreciated.

[medariox]

@labrys
I don't use NZBs, but I tried using nightly with TorrentToMedia.py and got this exception:

python C:\Users\Dario\Desktop\nzbToMedia\TorrentToMedia.py C:\Users\Dario\Desktop\sed
Traceback (most recent call last):
  File "C:\Users\Dario\Desktop\nzbToMedia\core\nzbToMediaUtil.py", line 1324, in __init__
    from win32.win32event import CreateMutex
ImportError: DLL load failed: %1 is not a valid Win32 application.

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "C:\Users\Dario\Desktop\nzbToMedia\TorrentToMedia.py", line 368, in <module>
    exit(main(sys.argv))
  File "C:\Users\Dario\Desktop\nzbToMedia\TorrentToMedia.py", line 287, in main
    core.initialize()
  File "C:\Users\Dario\Desktop\nzbToMedia\core\__init__.py", line 261, in initialize
    MYAPP = RunningProcess()
  File "C:\Users\Dario\Desktop\nzbToMedia\core\nzbToMediaUtil.py", line 1307, in __init__
    self.process = WindowsProcess()
  File "C:\Users\Dario\Desktop\nzbToMedia\core\nzbToMediaUtil.py", line 1328, in __init__
    from win32event import CreateMutex
ModuleNotFoundError: No module named 'win32event'

Running Windows 10 and Python 3.6.7

[p0psicles]

@medariox still needs a changelog