Sequence picking

[TheChymera]

The way COSplay currently picks sequences is somewhat intricate, and does no actually support randomized picking. This doesn't necessarily mean it should be changed (other than fixing randomization support), but the behaviour should either be simplified or precisely documented:

If the sequence_library directory contains:

• only files not named sequence*.tsv - the first file in alphabetical order is always picked
• files not named sequence*.tsv and files named sequence*.tsv - the first file in alphabetical order among the files named sequence*.tsv is picked
• only files named sequence*.tsv - the first file in alphabetical order among the files is picked

This is tested based on the terminal feedback from the COSplay CLI, with a sequence_library directory containing among others a .known_sequences directory repositing frequently used sequences under a <trial_ID>.tsv format - however, the presence and absence of this directory does not impact the picking behaviour.