support 256 colors

Closes #481.

Author: Qix-

src/node.js

@@ -25,6 +25,23 @@ exports.useColors = useColors;
 
 exports.colors = [6, 2, 3, 4, 5, 1];
 
+try {
+  var supportsColor = require('supports-color');
+  if (supportsColor && supportsColor.level >= 2) {
+    exports.colors = [
+      20, 21, 26, 27, 32, 33, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48,
+      49, 50, 51, 56, 57, 62, 63, 68, 69, 74, 75, 76, 77, 78, 79, 80, 81,
+      82, 83, 84, 85, 86, 87, 92, 93, 98, 99, 112, 113, 118, 119, 128, 129,
+      134, 135, 148, 149, 154, 155, 160, 161, 162, 163, 164, 165, 166, 167,
+      168, 169, 170, 171, 172, 173, 178, 179, 184, 185, 190, 191, 196, 197,
+      198, 199, 200, 201, 202, 203, 204, 205, 206, 207, 208, 209, 214, 215,
+      220, 221, 226, 227
+    ];
+  }
+} catch (err) {
+  // swallow - we only care if `supports-color` is available; it doesn't have to be.
+}
+
 /**
  * Build up the default `inspectOpts` object from the environment variables.
  *
@@ -92,10 +109,11 @@ function formatArgs(args) {
 
   if (useColors) {
     var c = this.color;
-    var prefix = '  \u001b[3' + c + ';1m' + name + ' ' + '\u001b[0m';
+    var colorCode = '\u001b[3' + (c < 8 ? c : '8;5;' + c);
+    var prefix = '  ' + colorCode + ';1m' + name + ' ' + '\u001b[0m';
 
     args[0] = prefix + args[0].split('\n').join('\n' + prefix);
-    args.push('\u001b[3' + c + 'm+' + exports.humanize(this.diff) + '\u001b[0m');
+    args.push(colorCode + 'm+' + exports.humanize(this.diff) + '\u001b[0m');
   } else {
     args[0] = new Date().toUTCString()
       + ' ' + name + ' ' + args[0];