counsel.el (counsel-ag, counsel-rg): store command persistently

[ericdanan]

This adds a new variable counsel-ag-command which stores counsel-ag-base-command including the optional extra-ag-args and is used by counsel-ag-occur. Also simplifies counsel-rg which now simply let-binds counsel-ag-base-command and calls counsel-ag (similarly to counsel-pt and counsel-ack).

This seem to solve issue #777 : counsel-pt and counsel-ack now work consistently when ivy-resume or ivy-occur is called (counsel-rg was not affected by this issue because it was duplicating the code from counsel-ag rather than calling it inside a let-binding).

It also solves issue #1462 which was closed because submitted about counsel-projectile-rg but actually affected counsel-rg and counsel-ag : extra args are now remembered when calling ivy-occur.

A couple of things to note:

• counsel-rg was not exactly duplicating the code from counsel-ag, there were small differences in the way extra args were read or initial directory was set. I've resolved them in the way that made more sense to me, but maybe they were intentional. Also in counsel-rg, the caller was set to counsel-rg but now it is counsel-ag, I don't know if that's an issue.
• In a way these changes make counsel-ag more similar to counsel-grep and it may be possible to make one rely on the other (eg counsel-ag-function / counsel-grep-function), but I didn't touch anything there. I noticed that the command used in counsel-grep-occur is different from counsel-grep-base-command, I don't know if that's on purpose.

Let me know if you would like me to make further changes.

[abo-abo]

Thanks, I like the simplification.

[isolet]

Is it intentionally to change the original behavior of doing ag from default-directory to .git based directory when initial-directory is nil?

[abo-abo]

@isolet Yes, this is intentional: I want to grep the whole project 95% of the time. For the other 5%, default-directory can be chosen by using C-u prefix.