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/10-creatures.otui

@@ -0,0 +1,10 @@
+Creature < UICreature
+  size: 80 80
+  padding: 1
+  image-source: /images/ui/panel_flat
+  image-border: 1
+  border-width: 1
+  border-color: alpha
+
+  $checked:
+    border-color: white