[qutebrowser] Per-domain editor.command, or equivalent

[David Nebauer]

I use gvim as external editor and want to be able to set a particular 
filetype when it is launched from a specific domain. One way to
"communicate" this from qutebrowser to gvim is that when launching from 
the specific domain, editor.command would include a "set filetype" 
command.

In case it matters, the specifics are that TiddlyWiki on my system uses 
http://localhost:10744 as its domain. The file opened by gvim has no 
extension and no content, so gvim cannot infer the file type by its 
usual means. This is why, when launching from that domain, I want gvim 
to set the filetype to 'tiddlywiki'. 

When I attempted to set a per-domain editor.command in config.py and 
source it, I received an error that editor.command does not support URL 
patterns.

Another option would be to embed the domain URL in editor.command in 
such a way that it is transferred to gvim, e.g., by using a vim option 
to set an internal vim variable with the URL. It appears, however, that 
the domain URL is not a parameter available to editor.command.

All of which leaves me stuck. I'm hoping some knowledgeable members of 
this list may have some suggestions.

Regards,
David