Implement one-hand versions for built-in hotkeys (left-right nav, etc.)

[jchang504]

Even for the current default hold key (escape), all the built-in hotkeys are nice and intuitive, but they can't be performed with one hand (even given my caps lock mapped to escape). It would be nice to have a one-hand (particularly, left hand) version of them available for when you have one hand on the mouse, as you might for certain types of web browsing. You could even just use some of the alphabet keys on the extreme left, like q, w, a, z. In that case, we'd probably have to make them fully customizable (in case the user would rather pick other letters). The other question is whether they should exist in addition to or replacing the current defaults. The former seems kind of confusing, so I'm thinking the latter. This seems relatively simpler to implement too as the built-ins would basically become like normal customizable hotkeys (customizable on the options page) but with special preset functionality (and we'd also allow non-alphabet hotkeys for these). This should probably be implemented along with #1.

[jchang504]

Maybe this would be more of an advanced/experimental feature (#49).