Rework zsh prompt

[zhimsel]

Goals

• Faster (most important)
• Cleaner looking
• No large dependencies (e.g. haskell for the git prompt)

Required information

• User/host (only if on a remote machine)
• Path (preferably truncated in some way)
• Git branch/status (fast or async)
• viins/vicmd mode
• Previous command's return code
• Previous command's run time (maybe)
• Indicator for backgrounded programs

To-do

• [x] Settle on a prompt plugin (or manually created one)
• [x] Configure said prompt
• [x] Move "env metadata" parts to ZLE widget that displays the value of the configured env vars or command outputs with support for local additions (note to self: zle -R [display-string]). Maybe include more-detailed git status?
• [ ] ~Figure out how to get git info to update when using the ^e ZLE widget.~

[zhimsel]

https://github.com/denysdovhan/spaceship-prompt https://github.com/denysdovhan/spaceship-prompt/blob/master/lib/section.zsh

[zhimsel]

https://github.com/sindresorhus/pure https://github.com/therealklanni/purity https://github.com/intelfx/pure https://github.com/dfurnes/purer