Fix multiple sessions per process

[Dregu]

When routing the W10 per-app audio output to a non-default device, some applications will open (inactive) sessions to multiple devices. Or some complex apps might do so on purpose. VC treats these sessions as duplicates even though they are on different outputs, which means only the first session can be adjusted, and it's usually the wrong one.

So I fixed that...

This PR:

• makes the duplicate check actually look for duplicate sessions, not only processes
• highlights inactive sessions in lists
• adds a setting to hide/ignore inactive sessions in the notification and next/previous hotkeys
• adds device name and flow direction to mixer and session notification
• adds a hotkey action to simply show a notification without changing anything
• fixes Volume control doesn't catch processes from different inputs #159
• targets all sessions when using target overrides (fixes Duplicate sessions with same name can't all be controlled by same active hotkey, is this intended? #153)
• adds active application notification, also used for target overrides (fixes [FEATURE] Show Notifications window when Active Application hotkeys are used #118)

Haven't tested this a lot, just what I have running currently, but then again there's not much to test. I also don't really know what I'm doing, so I might be doing something silly.

Some more clutter in the mixer, but not in the notification!

[Dregu]

I also have a branch messing with active application / target override notifications where all affected sessions are always shown, even if the sessions are otherwise hidden. I had to reorganize how the hidden sessions are stored and filtered though, cause it seemed like a big mess to me to figure out which list a VM is supposed to be in. It's even more experimental...

[radj307]

This looks great so far! 👍

[Dregu]

This looks great so far! 👍

I think so too! I've been rocking the active notifications for a week with no issues, except for the few corner cases with empty notification I just fixed, so that feature is also merged here now.