[feature request] Add both speakers sound and mic sound

[conualfy]

One basic thing about a screen recorder is to record both speakers' sound and mic sound. This is a missing feature in SimpleScreenRecorder, the one I otherwise use. I don't know exactly how complicated this would be, but there are plenty of situations when this is usuful. In my case, that would mean to either use the software I regularly use and also start another program just for the audio, later to mix audio and readd sound into the mkv video container file (it can be done without reencoding), or use OBS (I had some problems with output sound&video quality in the past (unreliable, I don't know the cause), plus it is a way too complex software for simple needs).