create add function that creates new enemies at a random time
add green dots

players health increases if it contacts a green dot, and decreases if it contacts a red dot
change max seconds between new dot to 5, and remove green dots from screen when they leave, not just when they are contacted with player
start the game when player clicks play button
remove canvas listener that triggers requestAnimation frame

the play button onlick event handles this
add thrust property to player that determines how much the player moves when arrow keys are press
stop game when health is 0 and add ability to restart game
a style fo play button
add readme
Merge pull request #9 from jamezb/dots

Dots