really messy first attempt at a platformer engine

system currently handles keyboard input using jquery.hotkeys.js, loads
level data from an external csv using jquery, draws level data, and
calculates collision detection with the implementation of the swept AABB
collision algorithm from
http://www.gamedev.net/page/resources/_/technical/game-programming/swept-aabb-collision-detection-and-response-r3084
update readme to include jquery.hotkeys
reworked collision detection and jumping mechanics

slide response computed using the normal vectors now stored under the
player object that are manipulated during the collision detection
algorithm. jump changed from up arrow to z and only fires once per
keypress
friction now compensates for floats
alpha camera system

controls changed again to help debug camera: movement is now mapped to
WASD, jump is space, camera is moved with arrow keys
new entity class
alpha projectile system

canvas now exists inside a div to make it easier for js to grab proper
mouse coordinates, lots of mouse input is now handled
projectiles now fire towards current mouse pos

trigonometry is hard
player moved from object literal to new class
collision handling block moved, test enemy added
projectiles now collide and kill creatures
level data format changed to JSON

i have no idea why i thought csv was a good idea
projectile firing delay introduced
tweaked projectiles
camera tracks player's position and orientation
bugfix: projectiles now use camera position too
read starting position from data file
creatures die from falling out of the level
dying resets player to checkpoint
bugfix: reset velocity upon respawn