Moved the calculation of relative kinetic energy into the main loop, for improved performance.
Added (temporary) console timers.
Merge branch 'master' into multi-threaded
Refactored trajectory.js to remove the global variable 'gravity' and updated the comments.
Moved the trajectory computations into a WebWorker thread.
Updated TODOs for this branch.
Make curves smoother by plotting on distance

The x axis of the graph is distance, so we will get much smoother lines
by choosing plot points that are evenly distributed by distance, rather
than time. The only caveat for this method is that the projectile can
obviously only go forwards (albeit not really a problem for this use)!

Note that this only affects projectiles with extreme deceleration.

Test case:
	Velocity = 30 (m/s)
	Angle = 0 (degrees)
	Height = 1.6 (m)
	Mass = 1 (g)
	Diameter = 30 (mm)
	Drag Coefficient = 5
	Gravitational Acceleration = 9.81 (m/s)
	Fluid Density = 1.29 (kg/m^3)
Remove potential multi-threaded race condition

If a trajectory is being computed by the background worker thread when
another is requested, the current thread will now be terminated before
the new one is created. This way a user will not be able to overload
their CPU, or cause one graph to override the other, by manically
pressing the 'Plot Trajectory' button! In addition to this, the
'Plot Trajectory' button is now temporarily replaced by a new
'Cancel Computation' button, to enable the user to cancel long-running
computations.
Fix bug with generatePNG()

The variable `graph` needs to be defined globally, in order for
generatePNG() to be be able to detect whether or not it has actually
been drawn.
Remove console usage

Unfortunately, Internet Explorer does not support the console object...
Update TODOs
Fix problem with generatePNG() in IE

For some reason the previous code was causing an error to be thrown in
Internet Explorer 10.
Merge branch 'multi-threaded'
Merge branch 'smooth-curves'
Add supported browsers list to README.md