Added missing keys definitions

src/raylib.h

@@ -103,11 +103,23 @@
 #define KEY_SPACE            32
 #define KEY_ESCAPE          256
 #define KEY_ENTER           257
+#define KEY_TAB             258
 #define KEY_BACKSPACE       259
+#define KEY_INSERT          260
+#define KEY_DELETE          261
 #define KEY_RIGHT           262
 #define KEY_LEFT            263
 #define KEY_DOWN            264
 #define KEY_UP              265
+#define KEY_PAGE_UP         266
+#define PAGE_DOWN           267
+#define KEY_HOME            268
+#define KEY_END             269
+#define KEY_CAPS_LOCK       280
+#define KEY_SCROLL_LOCK     281
+#define KEY_NUM_LOCK        282
+#define KEY_PRINT_SCREEN    283
+#define KEY_PAUSE           284
 #define KEY_F1              290
 #define KEY_F2              291
 #define KEY_F3              292