Add BrowserOpenURL and BrowserOpenFile to App.

Better WML assets for demo
Fix dialog responses.
Add `wml-openurl`
Rename: data-wml -> wml
Fix Alpha Feedback URL

v3/pkg/application/messageprocessor_browser.go

@@ -0,0 +1,43 @@
+package application
+
+import (
+	"github.com/pkg/browser"
+	"net/http"
+)
+
+const (
+	BrowserOpenURL = 0
+)
+
+var browserMethods = map[int]string{
+	BrowserOpenURL: "OpenURL",
+}
+
+func (m *MessageProcessor) processBrowserMethod(method int, rw http.ResponseWriter, _ *http.Request, _ Window, params QueryParams) {
+
+	args, err := params.Args()
+	if err != nil {
+		m.httpError(rw, "Unable to parse arguments: %s", err.Error())
+		return
+	}
+
+	switch method {
+	case BrowserOpenURL:
+		url := args.String("url")
+		if url == nil {
+			m.Error("OpenURL: url is required")
+			return
+		}
+		err := browser.OpenURL(*url)
+		if err != nil {
+			m.Error("OpenURL: %s", err.Error())
+			return
+		}
+		m.ok(rw)
+		m.Info("Runtime Call:", "method", "Browser."+browserMethods[method], "url", *url)
+	default:
+		m.httpError(rw, "Unknown browser method: %d", method)
+		return
+	}
+
+}