General improvements and multithreading / start stop issues fixed

[srmncnk]

This PR address general improvements and multithreading / start stop issues.

Please review and consider merging.

[srmncnk]

@ysak-y Can you please take a look at this and consider merging? Many thanks.

[ysak-y]

Hi @srmanc , thank you for your PR. I'll check until next Monday.

[ysak-y]

Checked. LGTM

[ysak-y]

Now I published new version v1.1.1 with your implementation. Thanks @srmanc !!
https://github.com/ysak-y/flutter_audio_capture/blob/master/CHANGELOG.md#111

[kijka]

@srmanc looks like there is an iOS issue #16
Do you have any ideas about what could be wrong?

[kijka]

@srmanc @ysak-y I've added a project to test and video demo of the bug to the #16

[ysak-y]

@srmanc What do you think about #16 ? As @vladsonkin reports, it seems be disabled after some time, and I guess it would be because of multithreading.

[srmncnk]

@vladsonkin @ysak-y Thanks for the reproducible example, I'll take a look this weekend.

[kijka]

@srmanc Thanks! Any ideas on how to fix it? Maybe it's the init block in SwiftFlutterAudioCapturePlugin?

[srmncnk]

Prepared a PR, please test it: #19