Range Support for :Tern* Commands

[jalcine]

When attempting to invoke :TernDoc over a particular statement, I intended to only pass a particular portion to Tern and I got

E481: No range allowed.

This issue is a matter of gauging interest to add support for passing in ranges for the Ex commands.

[marijnh]

I personally don't understand enough of Vim to have an opinion here. Most Tern query types do accept a range, so I guess if you could wire that up to Vim's ranges, it might be useful.