Silently fail to create output files when the specified output dir does not exist

[raymond-u]

Hello devs,

If I run "$ORNA -pair1 1.fa.gz -pair2 2.fa.gz -output test/test" in a folder where test/ does not exist, the program would silently fail, with no output files in test/. (And if run with added argument "-sorting 1", the program would complain about missing file in test/tmp/s0.fa.) This problem can be addressed by replacing mkdir() with a recursive one.

As a side note, I noticed that ORNA didn't try to remove *.h5 file when running in paired end mode, while it did do so in single end mode. I doubt if this is intentional since *.h5 is essentially a binary file.

Cheers