Refactor modules, closes #223

* All modules are sandboxed now
* All images,sounds,fonts,translations and styles were moved to "data" folder
* Reorganize image files folders
* Remove unmaintained modules: client_particles, client_shaders
* Implement new automatic way to load styles and fonts
* Add hide/show offline option in VipList
* Add invite/exclude to/from private channel in players menus
* Many other minor changes

data/styles/20-popupmenus.otui

@@ -0,0 +1,43 @@
+PopupMenuButton < UIButton
+  height: 18
+  margin-left: 5
+  margin-right: 5
+  margin-top: 1
+  margin-bottom: 1
+  size: 0 21
+  text-offset: 0 0
+  font: verdana-11px-antialised
+  
+  image-source: /images/ui/button_popupmenu
+  image-color: white
+  image-clip: 0 0 20 20
+  image-border: 2
+
+  color: #aaaaaa
+  background-color: alpha
+
+  $hover !disabled:
+    color: #ffffff
+    background-color: #ffffff44
+    image-clip: 0 40 20 20
+
+  $disabled:
+    color: #555555
+
+PopupMenuSeparator < UIWidget
+  margin-left: 2
+  margin-right: 2
+  margin-bottom: 1
+  image-source: /images/ui/menubox
+  image-border-left: 1
+  image-border-right: 1
+  image-clip: 0 0 32 2
+  height: 2
+  phantom: true
+
+PopupMenu < UIPopupMenu
+  width: 50
+  image-source: /images/ui/menubox
+  image-border: 3
+  padding-top: 3
+  padding-bottom: 3