Add "echo" as logger

This allow to test ouput, and specify ouput other then os.Stdout

echo/echo.go

@@ -0,0 +1,72 @@
+package echo
+
+import (
+	"fmt"
+	"io"
+	"os"
+)
+
+const (
+	colorReset  = "\033[0m"
+	colorRed    = "\033[31m"
+	colorGreen  = "\033[32m"
+	colorYellow = "\033[33m"
+	colorBlue   = "\033[34m"
+)
+
+var (
+	useColor bool      = false
+	output   io.Writer = os.Stdout
+)
+
+func Color(enabled bool) {
+	useColor = enabled
+}
+
+func Output(writer io.Writer) {
+	output = writer
+}
+
+func ErrorfMsg(format string, a ...interface{}) error {
+	msg := fmt.Sprintf(format, a...)
+	if useColor {
+		msg = fmt.Sprintf("%vError:%v %v", colorRed, colorReset, msg)
+	} else {
+		msg = fmt.Sprintf("Error: %v", msg)
+	}
+	return write(msg)
+}
+
+func InfoFMsg(format string, a ...interface{}) error {
+	msg := fmt.Sprintf(format, a...)
+	if useColor {
+		msg = fmt.Sprintf("%vInfo:%v %v", colorBlue, colorReset, msg)
+	} else {
+		msg = fmt.Sprintf("Info: %v", msg)
+	}
+	return write(msg)
+}
+
+func GreenMessageF(format string, a ...interface{}) error {
+	return writeWithColor(fmt.Sprintf(format, a...), colorGreen)
+}
+
+func YellowMessageF(format string, a ...interface{}) error {
+	return writeWithColor(fmt.Sprintf(format, a...), colorYellow)
+}
+func RedMessageF(format string, a ...interface{}) error {
+	return writeWithColor(fmt.Sprintf(format, a...), colorRed)
+}
+
+func writeWithColor(msg string, color string) error {
+	if useColor {
+		return write(fmt.Sprintf("%v%v%v", color, msg, colorReset))
+	}
+	return write(msg)
+
+}
+
+func write(msg string) error {
+	_, err := fmt.Fprintln(output, msg)
+	return err
+}