[Feature request] Custom keybidings

[NickCis]

The idea is to be able to change keybidings.

I'm a vim user, and I often use ctr+f / ctr+b for next / prev page. Current keybidings have ctr+f as search

[tommyjcarpenter]

Definitely +1; id like to map left-arrow and right-arrow to switch from the filelist to the diff; [1/2] is very unintuitive for my muscle memory.

[tommyjcarpenter]

#150