vlib/net: add buffered IO, x.net -> net (#6754)

examples/net_t.v

@@ -0,0 +1,23 @@
+import net.http
+import sync
+import time
+
+fn send_request(mut wg sync.WaitGroup) ?string {
+    start := time.ticks()
+    data := http.get('https://google.com')?
+    finish := time.ticks()
+    println('Finish getting time ${finish - start} ms')
+    wg.done()
+    return data.text
+}
+
+
+
+fn main() {
+    mut wg := sync.new_waitgroup()
+    for i := 0; i < 50; i++ {
+        wg.add(1)
+        go send_request(mut wg)
+    }
+    wg.wait()
+}