Error handling. Vendoring

Signed-off-by: Ettore Dreucci <ettore.dreucci@gmail.com>

vendor/github.com/dixonwille/wmenu/clearScreen.go

@@ -0,0 +1,36 @@
+package wmenu
+
+import (
+	"os"
+	"os/exec"
+	"runtime"
+)
+
+var clear map[string]func()
+
+func init() {
+	clear = make(map[string]func())
+	clear["linux"] = func() {
+		cmd := exec.Command("clear")
+		cmd.Stdout = os.Stdout
+		cmd.Run()
+	}
+	clear["darwin"] = func() {
+		cmd := exec.Command("clear")
+		cmd.Stdout = os.Stdout
+		cmd.Run()
+	}
+	clear["windows"] = func() {
+		cmd := exec.Command("cmd", "/c", "cls")
+		cmd.Stdout = os.Stdout
+		cmd.Run()
+	}
+}
+
+//Clear simply clears the command line interface (os.Stdout only).
+func Clear() {
+	value, ok := clear[runtime.GOOS]
+	if ok {
+		value()
+	}
+}