implement game configuration file

this integrates https://github.com/cktan/tomlc99 into the repo as a dependency

include/twn_input.h

@@ -41,9 +41,9 @@ typedef struct Button {
 typedef struct Action {
     size_t num_bindings;
 
-    /* if you bind more than NUM_KEYBIND_SLOTS (set in config.h) */
+    /* if you bind more than the number set in the configuration file */
     /* it forgets the first Button to add the new one at the end */
-    Button bindings[NUM_KEYBIND_SLOTS];
+    Button *bindings;
 
     Vec2 position;        /* set if applicable, e.g. mouse click */
     bool is_pressed;