Refactor key handling and add keybindings configuration for game actions

conf/keybinding_game.json

@@ -1,10 +1,10 @@
 {
 
-    "new_rat": ["Return", 13],
+    "new_rat": [["keyup", "Return"], ["keydown", "Return"]],
     "kill_rat": ["D"],
     "toggle_audio": ["M"],
     "toggle_full_screen": ["F"],
-    "scroll_up": ["Up", 8],
+    "scroll_up": [["keydown", "Up"], ["keydown", "Up"]],
     "scroll_down": ["Down", 9],
     "scroll_left": ["Left", 10],
     "scroll_right": ["Right", 11],

conf/keybindings.yaml

@@ -0,0 +1,19 @@
+keybinding_game:
+  keydown_Return: spawn_rat
+  keydown_D: kill_rat
+  keydown_M: toggle_audio
+  keydown_F: toggle_full_screen
+  keydown_Up: start_scrolling|Up
+  keydown_Down: start_scrolling|Down
+  keydown_Left: start_scrolling|Left
+  keydown_Right: start_scrolling|Right
+  keyup_Up: stop_scrolling
+  keyup_Down: stop_scrolling
+  keyup_Left: stop_scrolling
+  keyup_Right: stop_scrolling
+  keydown_Space: spawn_new_bomb
+  keydown_N: spawn_nuclear_bomb
+
+keybinding_start_menu:
+  keydown_Return: reset_game
+  keydown_Escape: quit_game