Paired-end reads

[HadrienG]

Issue to track the progress on the Roadmap item "Generate paired-end reads"

• Add insert_size parameters to the ArgumentParser
• Update the coverage calculations not necessary. The number of reads doesn't change!*
• Update read generator to output paired-end reads**
• Iterate over generator and write to 2 output files
• update test_generator.py

* The number of reads is divided by 2 in the generator function and taken as number of pairs
**We'll probably want to yield a tuple containing two SeqRecord objects: one with the forward read, the other with the reverse

[HadrienG]

closed with 3cec5aa ! Now the fun can begins with implementing error models 😟