Support for linenoise

[v217]

The minimal readline alternative written by the Redis inventor

https://github.com/antirez/linenoise

seems to offer all rc-shell needs.

[TobyGoodwin]

Uh, yeah, I started looking at this, but got distracted by another project, sorry. Hope to get back to it soon

[CasperVector]

I compared linenoise/linenoise-ng with editline, and find the latter to be smaller (speaking of static libraries) and seemingly less buggy. Of course, your mileage may vary.
EDIT: but editline does not quite care about Unicode. I was in a hurry; sorry for that.

[xyb3rt]

Closing, because we'd have to include linenoise's source files and the project has a lot of open issues and does not properly support non-ASCII input.