Fix allocation bug and some other

- Add *.core (core dumps) to .gitignore
- Change defines of directions to enum

.gitignore

@@ -1,2 +1,3 @@
 obj/
 game
+*.core

include/player.h

@@ -4,12 +4,7 @@
 #include <stdbool.h>
 #include "food.h"
 
-#define UP    0
-#define RIGHT 1
-#define DOWN  2
-#define LEFT  3
-
-typedef int Direction;
+typedef enum { UP, RIGHT, DOWN, LEFT} Direction;
 typedef struct player_node_t PlayerNode;
 typedef struct player_t Player;
 

src/player.c

@@ -45,6 +45,7 @@ bool playerDoTick(Player *player, Food food)
 {
     bool food_collision;
     PlayerNode *new_head = (PlayerNode *)malloc(sizeof(PlayerNode));
+    new_head->next = NULL;
     int head_x = player->head->x;
     int head_y = player->head->y;