Document and/or Provide Alternatives for SGR Across Vector Elements

[brodieG]

Implicitly, in:

x <- c('\033[31mhello', 'world')

fansi assumes that "world" is also to be colored red, i.e. as would happen with writeLines(x). So style carries through. This should probably be clearly documented, along with providing an option for treating each CHARSXP as if it were in its own insulate universe.