Constructs a new health bar at the given location with the given values
Draws the progress bar to the screen
Returns the location of the progress bar
Sets the location of the progress bar
The location and dimensions of the bar
The background color of the bar
The current value of the quantity measured
The forground color of the bar
The maximum value of the quantity measured
A progress bar to be displayed at any point on the screen Fills from left to right its progress TODO: allow bar direction to be modified