Add ranged combat support

* Clean up the CombatAction and Attack code to make it easier to use for
  range.

* Add collision detection to the distance checks before attacking in the
  CombatAction.

* Create a Ruby DSL for defining projectile types and fix the
  ProjectileUpdateOperation so it uses the correct position offset.

* Fix the packet structure of the HintIconMessageEncoder.

data/plugins/combat/weapons/ranged/crossbows.rb

@@ -0,0 +1,11 @@
+CROSSBOW_WIDGET_ID = 79
+
+create_weapon_class :crossbow, widget: CROSSBOW_WIDGET_ID, type: :ranged do
+  defaults animation: 426, speed: 6, range: 7
+
+  style :accurate, range: 7, button: 2
+  style :rapid, speed: 5, button: 3
+  style :long_range, range: 9, button: 4
+end
+
+create_weapon /rune c'bow/, :crossbow