iTerm2 Protocol support

[NSPC911]

unlike the name suggests, iTerm2's image protocol is also supported by a couple terminals. You can perhaps use the wookayin/python-imgcat to add it as a protocol

[lnqs]

Having a quick look in the protocol's docs it should be straight forward to implement. However, what I don't see in the docs is a way to query the terminal if the protocol is supported. If I don't miss something we'd need a database of terminals with their supported image protocols in the code -- I don't like the idea of maintaining that.
Do you see a way to get information about support?

[j4james]

There was a discussion about this on the xterm.js image repo a while back, and the suggestion was that you could potentially detect support for IIP by querying the cell size with OSC 1337 ; ReportCellSize ST, on the assumption that any terminal supporting that query would likely also support the iTerm2 image protocol. I haven't tested that myself, though, so I'm not sure how well it would work in practice.

See jerch/xterm-addon-image#58

[lnqs]

Thanks for the hint, @j4james. That might work (more or less reliably). I guess then there're no reasons to not give the implementation a try. I can have a look into that, but I can't make any promises when I find time to do so, probably not in the nearest future.
Anyway, I'm open to pull requests for adding support in the meantime.

[j4james]

FWIW, I just did some testing on the terminals I have that support IIP. Only two responded to the ReportCellSize query (Konsole and WezTerm). Four did not respond to that query (BobCat, Mintty, MLTerm, and Rio). So not exactly a great indicator, but perhaps better than nothing.