Use gb as alias

[sogaiu]

This PR is a suggestion to use gb as an alias as that seems to be what's most often used elsewhere when a shorter name is desired:

$ rg import\ ./new_gap_buffer\ :as --sort path
freja/evaling.janet
3:(import ./new_gap_buffer :as gap)

freja/input.janet
4:(import ./new_gap_buffer :as gb)

freja/main.janet
81:(import ./new_gap_buffer :as new_gap_buffer)

freja/render_new_gap_buffer.janet
5:(import ./new_gap_buffer :as gb)

freja/textarea.janet
2:(import ./new_gap_buffer :as gb)

[saikyun]

Sounds good. Thanks! :)