[Feature request] configurable keybinds

[darukutsu]

lets say pressing Ctrl-P will invoke $PAGER instead of built in feature when specified in config

[darukutsu]

The idea behind this was so I can search easier for keywords in PKGBUILD and that way check it. I also thought about potentially editing it :wq... Since in #48 I implemented option to bind <C-o> to open PKGBUILD in browser I'm not sure if editing PKGBUILD is worth it. Or maybe give separate keybind, so it's easier to check out both upstream and PKGBUILD.

[darukutsu]

I decided to change issue title since it's better idea to let users map actions to desired standard keybinds. I'm not talking about something extreme like key-chaining.

NOTE: still would need for PKGBUILD to be separate action