Addition of Pressure Gauge Script

The Script has public 2d Vector variables for size and position, and
will accept a texture to represent it visually.

To represent pressure, it has a public float called “totalPressure”,
which should be a value between 0.0 and 1.0.

This should be attached either to the Volcano prefab or the Main Camera.

Bugs:

(1) one or two lines of unnecessary code
(2) the stupid thing visualizes upside down!
Merge branch 'master' of https://github.com/CodyIsAwesome/Volcano