Make re-branding possible

[qzb]

Current name and description of the CLI have to be changed (obviously). To make such change possible, current CLI should be turned into a Go library which will be used to implement kilo command, and (possibly) other, branded versions of the CLI.

[gpolek]

Probably as a separate issue, we should introduce possibility to implement functions which checks for new versions of klio itself and commands / plugins as much extendable as possible.

[qzb]

@gpolek Yep, I was thinking about adding some kind of hooks functions which would enable implementing custom features like that. But indeed this should be a separate issue.