key mappings improvements(?)

[turlututututu]

Hi!

First of all, thank for making this open source, this is the nicest curse based editor I have seen so far!

I think, we could make the key mapping a bit more intuitive for vi user (or user in general). Currently 'j' moves the cursor up while in vi-like-editor it moves the cursor down. Furthermore, the key 'F1' and 'F10' are usually used by the terminal to display help/option. Thus we could map the help (F1) and the exit (F10) to more default friendly key. That being it does stay true to the tradition of user being enable to quit vi xD

(P.S: I am willing to do the change, if they fit you)