Implemented echo example

examples/echo/echo.q

@@ -0,0 +1,18 @@
+import mem
+import sys
+
+main() {
+	length := 4096
+	address := mem.alloc(length)
+
+	loop {
+		n := sys.read(0, address, length)
+
+		if n <= 0 {
+			mem.free(address, length)
+			return
+		}
+
+		sys.write(1, address, n)
+	}
+}