Build/PHPCS: improve check for superfluous whitespace in files

[jrfnl]

Apparently PSR2 turns a couple of the superfluous whitespace checks off.
This turns these back on.

There is one additional check turned off in PSR2 which I've left alone: the check for multiple blank lines in a row.
IMO, sometimes it's useful to use two blank lines to break up code for improved readability, so I'm quite happy to leave that one turned off.

[MarkMaldaba]

IMO, sometimes it's useful to use two blank lines to break up code for improved readability, so I'm quite happy to leave that one turned off.

I disagree that it is 'sometimes useful'. This implies that the developer adding the extra blank line is bestowing it with some kind of magic meaning that they expect other developers to understand, e.g. "this next bit is separate to that previous bit" or "now we're going to start generating the output" or whatever. This is not a good way to communicate, as no one else will know what you intended and will most likely assume it is a mistake. Or worse, add code before the double-break when it should be afterwards, or vice-versa, thus completely mangling the intended meaning.

In any situation where you think it would be useful to use multiple blank lines, you should be writing a comment instead.

Whether to turn the sniff on or off is really a question of how nitpicky you want to be, but as we're sniffing for trailing whitespace, which is probably the most nitpicky you can be, it feels that this one should also be turned on.

[wimg]

I kinda have to agree with Mark here : if it separates blocks of codes for readability, it might be good to either add a comment or split it up in a separate method.

[jrfnl]

Ok, maybe that was the dyslectic in me speaking. Most of the time (if not all), there's also a comment.

I'll fix up the commit in a little and fix the places in the codebase which don't comply (probably mostly introduced by me). will ping when done.

[jrfnl]

Ok, done. I've fixed up the original commit to include the "multiple empty lines" check and added two more commits:

1. Realized when adjusting the file that the ruleset used tabs not spaces: fixed.
2. Fixed violations against the newly enabled check in the existing codebase.