Move unnecessary calculations from draw and drawHitbox methods to constructor in Vehicle class
Change coordinates in Player class

-Add properties to hold x and y position in sprite sheet
-Add separate x and y for position in tiles and pixels
-Make appropriate changes in collision checks
Miscellaneous tweaks to Vehicle class

-remove hitbox property from constructor
-simplify an if statement in move method
-drawHitbox no longer accepts a color input
Merge Vehicle and Platform classes into a single Obstacle class
Populate river
Randomize animation time for each individual object
Set obstacle's hitboxes in the constructor
Float player when on water obstacles