Implement caching

[laughedelic]

All the __suggest_* functions use some output from brew and some of those commands are quite slow. It doesn't cache and every time you want to complete a formula name, it will run again.

• search if brew has some internal caching that could be used here
• write some cache files in XDG paths? how/when to invalidate them?
• can brew update be turned off on such commands? or can we hook to it to update the cache?

[laughedelic]

Note: there's something in ~/Library/Caches/Homebrew/desc_cache.json

[laughedelic]

It seems that desc_cache.json got deprecated, so the current cache lookup doesn't work now.

[benedictleejh]

Just thought I'd leave a comment here noting that ~/Library/Caches/Homebrew/descriptions.json that seems to contain formulae names and their descriptions. A quick search of Homebrew's repo suggest that it functions as a cache for Homebrew.