Moved theme into its own file, added message dialog state to show error messages, game install button is disabled when clicked and if there is an installer task pending or running

lib/states/boot.rb

@@ -2,6 +2,8 @@ class W3DHub
   class States
     class Boot < CyberarmEngine::GuiState
       def setup
+        theme(W3DHub::THEME)
+
         background 0xff_252525
 
         @fraction = 0.0
@@ -18,7 +20,7 @@ class W3DHub
           stack(width: 1.0, height: 0.925) do
           end
 
-          @progressbar = progress height: 0.025, width: 1.0, fraction_background: 0xff_00acff, border_thickness: 0
+          @progressbar = progress height: 0.025, width: 1.0
 
           flow(width: 1.0, height: 0.05, padding_left: 16, padding_right: 16, padding_bottom: 8, padding_top: 8) do
             @status_label = caption "Starting #{NAME}...", width: 0.5