Too strict definition of 'horizontal' for touchpads.

When using a touchpad, the scrolling action is rarely - if ever - absolutely horizontal or vertical, but almost always somewhat slanted. This means that when the intention is to scroll vertically, the scrolling action will also be somewhat (if ever so slightly) horizontal and therefore simultaneously scroll in time. Obviously this is somewhat annoying and also makes it difficult to use the correct version (at least whenever the correct one isn't the last one).

Perhaps it would be better if scroll-through-time compared the horizontal component to the vertical component and only applied its time machine magic if the horizontal component where larger than the vertical. Or perhaps it should be a user setting (although I can't imagine why one would intentionally scroll in both time and space simultaneously, I would have to admit that some (many?) have habits I don't fully understand so it's supposedly possible), perhaps then including at which threshold it should start to interact. My vote is for not having a user setting though: K.I.S.S.

Atom : 1.17.2
Electron: 1.3.15
Chrome : 52.0.2743.82
Node : 6.5.0

Kernel: 4.4.0-79-generic x86_64 (64 bit gcc: 5.4.0)
Desktop: Cinnamon 3.2.7 (Gtk 3.18.9-1ubuntu3.3) dm: mdm Distro: Linux Mint 18.1 Serena

The issue names no files, tests, or entry points, so begin by reproducing touchpad scrolling in the scroll-through-time behavior described. Inspect how horizontal and vertical components are handled; done means slight horizontal movement during vertical scrolling no longer changes time, while intentionally horizontal scrolling still does.

Written by the indexing model from the issue text.