Don't attempt to correct arguments

Prevents annoying false positives like correcting `git bd` to `git db`.
Also update topic branch before git ready
Ignore generated coverage from ag
Update `git ready` alias
Remove diffconflicts

* fugitive.vim's Gdiff is more useful
Use combined number/relativenumber mode

* Show actual line number for line at cursor
* Show relative line numbers for other lines
Don't attempt to correct spelling

* False positives are common
* Seeing the error and retyping is usually faster anyway
Remove rbenv init

* Faster shell load
* Just set path by hand in zshenv
* Allows putting rbenv somewhere besides the front of the path