Add -e/--pattern option

[rzlourenco]

grep provides an option to use an explicit pattern. This is useful since we may need to search for a pattern that starts with - or --.

[RomanHargrave]

As far as my experience goes, this can be done already:

ag --fish -- '--flag' scripts/ should work, as it would with GNU grep make install | grep -v -- '-- Up-to-date'.

[bishopb]

See also the earlier PR #672 that already implemented this. That said, the -- workaround by @RomanHargrave makes sense.

[wsdjeg]

I still prefer use an option instead of seperator. I just check ripgrep, it support -e option, after -e option I can use any string.

[orgads]

👍