Calculate delta-time from audio clock rather than using the `time` crate.

[mitchmindtree]

[errordeveloper]

I am not quite sure if simply replacing precise_time_ns() with stream.get_stream_time() would be sufficient, there may be more refactoring needed, but that would be a good starting point, I suppose...

[errordeveloper]

I might try a basic test where precise_time_ns() would be printed along with stream.get_stream_time() and find out what difference there in their values.

[errordeveloper]

So precise_time_ns() as f64 / self.stream.get_stream_time() results in some jittery numbers, but don't take my word on that yet, I need to do more tests.

[bvssvni]

Perhaps use clock_ticks? https://github.com/tomaka/clock_ticks