Remove trailing whitespace from python code

[sparr]

Not the most glamorous first PR, I know. Most of the edits are lines containing just spaces, but a few are actual trailing whitespace on code lines.

I won't be offended if this isn't merged. I'll be rebasing all my other branches on/off this one, so I can maintain it locally if necessary, but I thought I'd submit it just in case it's welcome.

[thisismypassport]

Hi, thanks for the PR, but I don't see a reason for it - I'm fine with trailing whitespaces, especially on blank lines in the middle of methods.