Try to support Keepalive Timeout, expose 'streams check' for Connection

src/proto/connection.rs

@@ -242,6 +242,11 @@ where
         }
     }
 
+    /// Checks if there are any streams
+    pub fn has_streams(&self) -> bool {
+        self.inner.streams.has_streams()
+    }
+
     /// Checks if there are any streams or references left
     pub fn has_streams_or_other_references(&self) -> bool {
         // If we poll() and realize that there are no streams or references

src/server.rs

@@ -553,6 +553,11 @@ where
         self.connection.take_user_pings().map(PingPong::new)
     }
 
+    /// Checks if there are any streams
+    pub fn has_streams(&self) -> bool {
+        self.connection.has_streams()
+    }
+
     /// Returns the maximum number of concurrent streams that may be initiated
     /// by the server on this connection.
     ///