Huge refactor regarding concurrency.

Now we have pooler which will pool connections (like pinging),
so there will be no timeouts due to "we have launched 100000 goroutines".

Reworked all code to use events (see Eventer). Still more work about
this to go.

Maybe more fixes I forgot.

cachemodels/server.go

@@ -0,0 +1,24 @@
+// URTator - Urban Terror server browser and game launcher, written in
+// Go.
+//
+// Copyright (c) 2016, Stanslav N. a.k.a pztrn (or p0z1tr0n)
+// All rights reserved.
+//
+// Licensed under Terms and Conditions of GNU General Public License
+// version 3 or any higher.
+// ToDo: put full text of license here.
+package cachemodels
+
+import (
+    // local
+    "github.com/pztrn/urtrator/datamodels"
+
+    // Other
+    "github.com/mattn/go-gtk/gtk"
+)
+
+type Server struct {
+    Server *datamodels.Server
+    TreeIter gtk.TreeIter
+    IterSet bool
+}