Update CAquarium.cpp

Added functionality for Clean and Feed

-Feed and Clean functions
-"If" statements for loading the other 3 "dirty" background images we need to use
-"If" in OnDraw to determine which background to load
-"If" in OnDraw to determine if fish are too hungry, and die (NOTE:  currently, fish are deleted if not fed after 30 seconds, so they disappear entirely.  However, my first solution to this segfaulted, so I'm working on something else.  Meanwhile, I have an iterator that deletes all items, including fish, but the treasure chest and other non-fish decor are deleted as well)