fix: colorization errors

- Corrects an error with `--search`. Previously, `--search` was not
  aware of whether it was outputted to a TTY, and would apply colorization
  at all times. This resulted in unwanted behavior when, for example,
  piping search results into a paginator.

- Corrects an error with `--color`. Previously, `--color` would be
  ignored if output was being written to a non-TTY. This made it
  impossible, for example, to `cheat tar --color | less -R`, as
  colorization would always be stripped. The behavior of `--color` has
  been modified such that it now behaves similarly to `--color=always` in
  other applications.

internal/config/color.go

@@ -0,0 +1,26 @@
+package config
+
+import (
+	"os"
+
+	"github.com/mattn/go-isatty"
+)
+
+// Color indicates whether colorization should be applied to the output
+func (c *Config) Color(opts map[string]interface{}) bool {
+
+	// default to the colorization specified in the configs...
+	colorize := c.Colorize
+
+	// ... however, only apply colorization if we're writing to a tty...
+	if !isatty.IsTerminal(os.Stdout.Fd()) && !isatty.IsCygwinTerminal(os.Stdout.Fd()) {
+		colorize = false
+	}
+
+	// ... *unless* the --colorize flag was passed
+	if opts["--colorize"] == true {
+		colorize = true
+	}
+
+	return colorize
+}