Displays time realtime, ability to jump around in time

Time is now displayed in top left corner of the window. It changes to accommodate for fast forwarding and for jumping in time.
Note that currently, time is an arbitrary number that starts at 0 when the simulation starts

The user is now able to jump to a certain point in time using the text input box and the "jump!" button underneath it. The user needs to enter the time they want to go to in the input box and press jump.
Note that this feature only works with positive values of time.

If the objects don't seem like they are moving it might be because they are moving too slowly to see, try fast forwarding to see motion.

Thanks!

Chris-- the code in this section and the code in line 912 is very similar, however the difference is that this code (timeJump) calculates everything from the initial position and velocity values, while the code on line 912 calculates everything from the current position and velocity values. Not sure if we will be able to create one function that does both of those things since one is calling a vector and another is calling an array for information.

Herman-- currently, the sample does not support negative time, however I think the three of us need to discuss if we want to support that and how we can allow the user to go back in time. What would be the advantages of changing it to an unsigned double?