[Biopython] Syntax colouring in Biopython Tutorial PDF

[Peter Cock]

Dear Biopythoneers,

As you know, our tutorial is on the website as HTML and PDF here,
usually updated only with each new release:

http://biopython.org/DIST/docs/tutorial/Tutorial.html
http://biopython.org/DIST/docs/tutorial/Tutorial.pdf

I'd appreciate a few eyes on this new PDF version of our Tutorial,

https://github.com/biopython/biopython/files/3192136/Tutorial.pdf

Comments on the content are great, but here the changes of interest are
to use syntax coloring for the Python snippets, Python console snippets
(the lines starting >>> etc), and the occasional bash console snippets.

I am particularly keen to hear from people using various PDF viewers -
does it looks fine, and importantly if copy-and-paste works as expected.
(It seems fine on Apple Preview on macOS)

Specifically, are the quotes, hyphens, and indentation copied as plain
text suitable for use directly in a Python script or terminal?

(Some approaches may look nice, but have problematic characters,
or loose the indentation on copy-and-paste)

The relevant pull request is here, comments by email or on GitHub
are welcome:

https://github.com/biopython/biopython/pull/2068

I know this doesn't add colours to the HTML output (done via hevea),
but we're looking at moving to Sphinx and perhaps Read-The-Docs -
more on that at a later date.

Thanks,

Peter