[Feature Request] add support for stderr/switching output destination

[inunix3]

I'd like to use this library for REPL for my interpreter, but since it also provides useful functions like ic_printf, which supports bbcode, I'd also like to use it for diagnostics.

But the problem is that all compilers and interpreters I've used output all warnings and errors to stderr, and that is a logical destination for these kinds of messages. But isocline doesn't offer any way to switch the output stream.

I see, that internally it has a function term_new() and the last parameter is fd. This function is called only once, and this fd parameter is hardcoded to -1.

Maybe I'm blind, but I didn't find anything in the API to change the output destination.