Improve support for Windows platforms

This enables ANSI support on older Windows versions and ensures correct
rendering when using the classic command prompt.

console_windows.go

@@ -0,0 +1,23 @@
+// +build windows
+
+package main
+
+import (
+	"os"
+
+	"golang.org/x/sys/windows"
+)
+
+// enableAnsiColors enables support for ANSI color sequences in Windows
+// default console. Note that this only works with Windows 10.
+func enableAnsiColors() {
+	stdout := windows.Handle(os.Stdout.Fd())
+	var originalMode uint32
+
+	windows.GetConsoleMode(stdout, &originalMode)
+	windows.SetConsoleMode(stdout, originalMode|windows.ENABLE_VIRTUAL_TERMINAL_PROCESSING)
+}
+
+func init() {
+	enableAnsiColors()
+}