[Feature request] Export lf options to shell commands

[SeerLite]

I want a keybind that toggles between these two settings:

set nopreview
set ratios 1

set preview
set ratios 1:3:2

I couldn't come up with any way to get this behavior by reading the :doc. But two came to mind:

1. Export lf options as shell variables (like Kakoune). Example: Exporting preview as $lf_preview (0/1).

%{{
    if [ $lf_preview -eq 1 ]; then
        # first setting here
    else
        # second setting here
    fi
}}

2. Implementing return codes for lf -remote "send $id <...>" depending on if the command succeeded or not. This is a hackier solution but I figured it'd work since set preview will fail if ratios are not set up correctly. If the above is implemented instead, I think this would still have other uses (can't come up with any right now though).

%{{
    if ! lf -remote "send $id preview"; then
        # second setting here
    else
        # first setting here
    fi
}}

I hope I didn't miss a more obvious way to set this up, this is the best I could come up with after reading the doc for a bit.

And thanks for lf! I feel like it complements the Kakoune workflow a lot.

[gokcehan]

@SeerLite Thanks for the ideas. This is mentioned frequently but unfortunately not added yet. I think I'm in favor of the first option. I don't think this would be difficult to implement either. If anyone is interested, I think one should simply add a new function like app.exportOpts to be called in app.runShell that goes over all options in gOpts and export them as variables.

Anyway, closing this as a duplicate for #376

[gokcehan]

@SeerLite Or let's just keep this open since you describe the feature better than the other issue.