Migrate notes.sh into an `nb` plugin

[apatel762]

Convert the whole script into an nb plugin so that I don't have to have a reference to it in my .bashrc.

And then while I'm at it, improve the journal workflow:

Ideas

• Natural language input to create new notes e.g. tomorrow will make (or open) tomorrow's fleeting note file; today will open today's; next week will create (or open) the note file for whatever day is 7 days from now, etc. using the built-in GNU date function
• Filter down existing journal notes in descending date order

[apatel762]

call it nb journal

with no parameters it will just open today's note, otherwise it can open notes based on the parameter (by passing the param directly to the GNU date command

Foam uses the below snippets as a shorthand reference to certain dates (see daily notes):

Snippet	Date
/tomorrow	tomorrow
/yesterday	yesterday
/monday	next Monday
/+1d	tomorrow
/-3d	3 days ago
/+1w	in a week
/-1m	one month ago
/+1y	in one year

I think supporting something like this would be good enough

[apatel762]

as for the notational velocity style of searching for + opening notes, could make a plugin that you call by running nb fzf like issue 102 in the nb repo

also, completely unrelated but you can jump between files in vim using gf! I didn't know that. Source: https://stackoverflow.com/questions/26919972/follow-link-in-vim-with-markdown-syntax (the vim docs are probably a better source but cba to look through them right now)