Ico's nwjs 04x branch with all fixes added, rebased on current master

Hi Jonathan, the title says it all! As far as I can tell, we've found and fixed (i.e., Ico fixed what I had found) all regressions on older nw.js (cf. !411 (merged)). I've also tested this extensively on Linux, running it for the past few days, and checked that it works on Mac and Windows as well. There don't seem to be any performance regressions on older nw.js either, so I'd say that this ready to to go in. Merge it while it's hot. :)

Note that I rebased this on the current master, so that this time we don't get the commits in this branch jumbled up with other stuff that's been going into master in the meantime. I didn't bother squashing the commits, but I can still do that if you want. I also fixed the conflict on scripts/regression_tests.pd due to an added regression test, so you might want to review that patch and see whether I've done that correctly (I think so).

@ico You may notice that I've actually pushed this as a separate ico-nwjs-04x-rebased branch now, and for the time being kept the original ico-nwjs-04x branch that you might already have checked out in your local clone; I've given you enough of a hard time with git pull --rebase these past days. (Please note, however, that these two branches, while containing the same commits, are not the same; this one is rebased on current master, the other isn't!) Anyway, it was a pleasure working with you again, and I'm looking forward to the stuff that you already have in store. Only this time please submit on a separate feature branch, please. ;-) You want to branch that from ico-nwjs-04x-rebased (this branch), or the master branch once Jonathan has merged this into master. I''ll be happy to help with testing and integrating again (and, as the semester holidays start next week, I'll also have more time to do so), so feel free to get in touch.