Few tweaks, changes

- RPG class variables organized into categories at top (map, sound,
player/monster, booleans, etc). static vars in all caps at top
- made walking delay, battle frequency, and number of sprites into
static variables
- OCD: tabs, spaces
- try-catch in HUD to prevent null ptr exception when getting a
non-existent inventory equipment
- break statements (saves one integer comparison) in player.java
- removed delay(20) in DrawMap