New module: Porechop

[jfy133]

Adds module for Porechop

• This comment contains a description of changes (with reason)
• CHANGELOG.md has been updated

• There is example tool output for tools in the https://github.com/ewels/MultiQC_TestData repository or attached to this PR: Add test data for Porechop module test-data#235
• Code is tested and works locally (including with --lint flag)
• docs/README.md is updated with link to below
• docs/modulename.md is created
• Everything that can be represented with a plot instead of a table is a plot
• Report sections have a description and help text (with self.add_section)
• There aren't any huge tables with > 6 columns (explain reasoning if so)
• Each table column has a different colour scale to its neighbour, which relates to the data (eg. if high numbers are bad, they're red)
• Module does not do any significant computational work

Example output:
multiqc_report.zip

[jfy133]

I think tests are failing possibly because it's taking too long to search for the string inside each log file... need to work out how to speed up I guess . I guess theoretically via number of lines but I'm not sure if this is consistent between porechop runs, will need to compare

[ewels]

I'm tempted to combine the 3 plots into 1, with 3 datasets. Feels quite verbose for fairly simple stats. But I'll leave it for now as it's late and I should be in bed.

It's an easy change if you agree though: https://multiqc.info/docs/#switching-datasets

[jfy133]

Thanks @ewels ! I wasn't sure what was the normal practise here, looking through other examples it looked like switching was between counts and percentages, and the percentages were calculated by the module itself and wasn't derived from the log files themselves.

Therefore in this case were the percentages were in the porechop log files, I thought it better to plot each set of raw data separately - but I have no preference either way.

[ewels]

I don't mean the percentages really - that bit is fine. I more meant combining the plots of the three different metrics (start, end, split) into one section / plot. Just with tabs to move between them. Each would still have counts / percentages in the same way.