move animation cache from play_controller to only fcn that uses it

This allows us to eliminate two headers and move code out of
play_controller, and keep related code together. The cache is
now a static variable in the only function that calls it.

src/play_controller.cpp

@@ -52,7 +52,6 @@
 #include "synced_context.hpp"
 #include "tooltips.hpp"
 #include "unit.hpp"
-#include "unit_animation.hpp"
 #include "unit_id.hpp"
 #include "whiteboard/manager.hpp"
 #include "wml_exception.hpp"
@@ -102,7 +101,6 @@ play_controller::play_controller(const config& level, saved_game& state_of_game,
 	controller_base(ticks, game_config, video),
 	observer(),
 	savegame_config(),
-	animation_cache(),
 	prefs_disp_manager_(),
 	tooltips_manager_(),
 	events_manager_(),

src/play_controller.hpp

@@ -36,7 +36,6 @@ class saved_game;
 class game_data;
 class team;
 class unit;
-class unit_animation;
 
 namespace actions {
 	class undo_list;
@@ -172,7 +171,6 @@ class play_controller : public controller_base, public events::observer, public
 	events::mouse_handler& get_mouse_handler_base();
 	events::menu_handler& get_menu_handler() { return menu_handler_; }
 
-	std::map< std::string, std::vector<unit_animation> > animation_cache;
 	static const std::string wml_menu_hotkey_prefix;
 protected:
 	void slice_before_scroll();

src/unit_animation_component.cpp

@@ -17,8 +17,6 @@
 #include "config.hpp"
 #include "display.hpp"
 #include "map.hpp"
-#include "play_controller.hpp"	//Only needed to access animations cache
-#include "resources.hpp"	//Only needed to access animations cache
 #include "preferences.hpp"
 #include "unit_animation.hpp"
 #include "unit.hpp"
@@ -199,7 +197,8 @@ void unit_animation_component::apply_new_animation_effect(const config & effect)
 	if(effect["id"].empty()) {
 		unit_animation::add_anims(animations_, effect);
 	} else {
-		std::vector<unit_animation> &built = resources::controller->animation_cache[effect["id"]];
+		static std::map< std::string, std::vector<unit_animation> > animation_cache;
+		std::vector<unit_animation> &built = animation_cache[effect["id"]];
 		if(built.empty()) {
 			unit_animation::add_anims(built, effect);
 		}