WIP: Adopt concolor-control for auto-detection

[epage]

This is a PoC to collect feedback on a crate meant improve
interoperability across various colored output crates.

I'm a little uncertain on the Buffer

• It handles console differently than WriterInner
• I used the lowest common denominator of the streams but I wonder if we
  should add support for completely skipping stream detection

For more on the motivation, see rust-cli/team#15 (comment)

[epage]

One blocker for termcolor adopting this is supporting termcolors MSRV. That should be a relatively straightforward transition that I'll hold off on once we've determined this is worth pursuing.

[epage]

@BurntSushi any input on what concolor-color needs for being adopted into termcolor on the path to resolving rust-cli/team#15?

Blockers I know of

• A 1.0 release (blocked, waiting on any termcolor adoption input to allow for breaking changes)
• MSRV (blocked, consolidating with other input)