Feature request: make console an optional dependency

[matklad]

At the moment insta library uses console as a dependency, which pulls in a number of other deps, including heavy ones like regex. My understanding is that this is not the core functionality: monochrome diffs are workable, and you always can use insta binary to get extra colors. So, for users which want to minimize dependencies, it would be beneficial if console could be disabled.

[mitsuhiko]

I rather cut down on the dependencies of console. Regex in particular could be made optional if certain features are removed.