Also create a Button class, and add buttons for:

• Quit
• Reset
• Boat turnaround
• Catch fish

SUMMARY:
• Sky is light blue by day; darker by night.
• Sea is bluish-green (or greenish-blue),
  occupying the lower 2/3 of the sketch,
  with brown mud along the bottom.
• On the surface (1/3 from the top),
  a red fishing boat sails back and forth,
  while a big fish swims back and forth, beneath.
• Title, author, and score are displayed in every frame.

EVENTS:
• Click near the fish (or press the 'f' key) to reset the fish:
  • Start fish on left side (X=0).
  • Set fish speed to random value.
  • Set fish to random depth.
• Click near the boat (or press 'c' key) to catch the fish.
  • Each attempt subtracts one from the score.
  • If boat is above fish (X within 10 pixels), fish is caught:
    • Add + 5 to score if daytime.
    • Add + 10 to score if nite.
    • reset fish (as above).

SCENE
• SKY: light blue when day is true; darker at nite.
• SUN: yellow circle; moves right during daytime (not visible at nite).
  When sun reaches right side, it becomes nite; later, day begins and sun reappears on the left.
• OCEAN: bluish-green (or greenish-blue); occupies 2/3 of ketch.
• MUD: Lowest 8 pixels are brown.
  

BOAT: Red boat moves on surface.
• Boat moves (right or left) by boatDX each frame;
• When boat reaches right side, it reverses direction.
• When boat returns to left side, it reverses direction AND changes speed randomly (between 2 and 5
• When boat reverses direction, make sure it is pointing forward.)
• CLICK near the boat to catch fish -- if it is underneath.

FISH: Fish swims back and forth, underwater.
• Fish moves (right or left) by fishDX each frame;
• When fish reaches left or right side, it reverses direction
  AND changes speed to random value.
• When fish reverses direction, make sure it is pointing forward.
• CLICK nearby to reset fish (to left side; random height & speed).

MESSAGES
• Title: large and centered at the top)
• Author at the bottom-right).
• Score is always displayed (on the upper-right)