[Add] precursor isolation window and precursor purity

[oliveralka]

Added a short explanation and image of the precursor isolation window. I was not able to find any example in regard to precursor purity, so I added that in addition.

fixes #206

[oliveralka]

I guess this fails since the "PrecursorPurity_input.mzML" is not on the master branch yet (introduced in this PR).

If it is better for testing I can also split up the PR and use one explicit for the new file.

[jpfeuffer]

Why do we do this urlretrieve at all? Binder includes all data from the repo.

[jpfeuffer]

And in Actions, of course everything is present as well.

[oliveralka]

As far as I have understood, we did it that way that if someone wants to copy & paste the code it is runable without using the binder integration.

[oliveralka]

And in Actions, of course everything is present as well.

Yes, but if it wants to retrieve the file from the current master branch - then it does not work or? https://raw.githubusercontent.com/OpenMS/pyopenms-extra/master/src/data/PrecursorPurity_input.mzML -> 404: Not Found

[jpfeuffer]

yes, will never work. https://github.com/OpenMS/pyopenms-extra/issues/220

[timosachsenberg]

As far as I have understood, we did it that way that if someone wants to copy & paste the code it is runable without using the binder integration.

Yes, that was the main reason.

[oliveralka]

I understand the issue, but I think this should be handled in another PR for all urlretrieve statements.

[timosachsenberg]

agree but what about the wrong code to retrieve the precursor spectrum?

[oliveralka]

Yes, I think we should have a helper function for python as well. I will open an issue and take a look.

[timosachsenberg]

thanks!