add pulseaudio event listener (replaces main window pactl listener), …

[Fl1tzi]

…add docstrings, fix startup if there are no hardware devices and optimize server status in main

Description

Please include a summary of the change and which issue is fixed. Please also include relevant motivation and context. List any dependencies that are required for this change.

It would be great if you try these changes before you merge them.

Fixes #51

Type of change

Please delete options that are not relevant.

• [x] Bug fix (non-breaking change which fixes an issue)
• [x] New feature (non-breaking change which adds functionality)
• [x] Breaking change (fix or feature that would cause existing functionality to not work as expected)
  • ^C does not work as expected but can be still closed with tray

Checklist :

You don't need to do all of this, but at least check what you did

• [x] My code follows the style guidelines of this project
  • I really tried to follow pep8
• [x] I have performed a self-review of my own code
• [x] I have commented my code, particularly in hard-to-understand areas
• [ ] I have made corresponding changes to the documentation
• [x] My changes generate no new warnings
• [ ] I have added tests that prove my fix is effective or that my feature works
• [ ] Any dependent changes have been merged and published in downstream modules

[Fl1tzi]

Okay I just noticed you probably also have to pulsectl_async to the dependencies, sorry!