refactored and added game save function (key: s)

system.go

@@ -0,0 +1,11 @@
+package main
+
+import "runtime"
+
+// returns current memory usage in MB
+func GetMem() float64 {
+	var m runtime.MemStats
+	runtime.ReadMemStats(&m)
+
+	return float64(m.Alloc) / 1024 / 1024
+}