Avoid divide-by-zero if no channels found

Avoid triggering assertion failure in ope_encoder_drain when closing having written an empty output file

Further build fix

Build fixes for namespace

Remove "using namespace std" throughout. Because the various stream sources are included into a single file, an instance of this in an earlier file can interfere with system headers included in a later one (as happens with Windows and std::byte).

Don't print errors as well as returning them

Pick up frame count

Comment only

Further doc note

Doc note

Merge from branch estimated-duration

Doc notes

Now that readExpectedTag skips mismatched chunks, we don't want to use it for the WAVE tag, which is not a chunk

Document + reorder the audio readers

Copyright date

Small tidy

Merge from default branch

Don't use HAVE_MINIMP3 in the default makefile, as it depends on something that package managers won't generally have provided

Update copyright dates

Always skip all non-matching chunks when seeking for a specific chunk; read only the defined amount of data from the data chunk