Add unscientific string vs. enum benchmarks.

You should take this with a grain of salt.

benchmarks/bench.d

@@ -0,0 +1,80 @@
+import std.stdio;
+import std.string : format;
+import std.datetime : comparingBenchmark;
+
+void main()
+{
+  auto bs = comparingBenchmark!(testColorizeString, testColorizeEnum,
+      10_000);
+
+  writeln("string : ", bs.baseTime);
+  writeln("enum   : ", bs.targetTime);
+  writeln("point  : ", bs.point);
+}
+
+static enum color : int
+{
+  black = 30,
+  red = 31,
+  green = 32,
+  brown = 33,
+  blue = 34,
+  magenta = 35,
+  cyan = 36,
+  gray = 37,
+  bg_black = 40,
+  bg_red = 41,
+  bg_green = 42,
+  bg_brown = 43,
+  bg_blue = 44,
+  bg_magenta = 45,
+  bg_cyan = 46,
+  bg_gray = 47,
+  bold = 0
+}
+
+void testColorizeString()
+{
+  auto str = colorize("this is blue", "blue");
+}
+
+void testColorizeEnum()
+{
+  auto str = colorize("this is blue", color.blue);
+}
+
+string colorize(const string str, const string color) pure
+{
+  int color_num = 0;
+  switch (color) {
+    case "black":   color_num = 30; break;
+    case "red":     color_num = 31; break;
+    case "green":   color_num = 32; break;
+    case "brown":   color_num = 33; break;
+    case "blue":    color_num = 34; break;
+    case "magenta": color_num = 35; break;
+    case "cyan":    color_num = 36; break;
+    case "gray":    color_num = 37; break;
+
+    case "bg_black":    color_num = 40; break;
+    case "bg_red":      color_num = 41; break;
+    case "bg_green":    color_num = 42; break;
+    case "bg_brown":    color_num = 43; break;
+    case "bg_blue":     color_num = 44; break;
+    case "bg_magenta":  color_num = 45; break;
+    case "bg_cyan":     color_num = 46; break;
+    case "bg_gray":     color_num = 47; break;
+
+    case "bold":        color_num = 0; break;
+
+    default:
+        throw new Exception("unknown color \"" ~ color ~ "\"");
+  }
+
+  return format("\033[%dm%s\033[0m", color_num, str);
+}
+
+string colorize(const string str, color c) pure
+{
+  return format("\033[%dm%s\033[0m", c, str);
+}