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- Move grep-alias path to variable.
- Use <<< "" instead of piped echo to check grep flags.
- Remove check for --color only since it's the same release as --exclude.

This version tries whether grep supports all the flags together
and progressively checks older flags if the grep test fails.
This means only one grep call if all flags are supported, and
one additional call for every flag that's not supported, up to
a maximum of 3 calls.

- Use $ZSH_CACHE_DIR to store the grep alias with all the right features
- Expire the cache after 24 hours
- See issue #8444

cvs's metadata is under CVS and not .cvs

Fixes #2641, #2642

Fixes #2641, #2642

Moving all zsh config options into a lib/ subdirectory to make way for some upcoming changes to directory structure and configuration options