Random Number Generation

[rstoneback]

Random number functions work best when they generate many numbers are once, which isn't always convenient. Python generators offer a solution to this, but they aren't conveniently carried around. Create two random number generator functions, one normally distributed, the other in a top hat distribution, and attach them to the pysat object at instantiation.

Plan:
- Create random number generators, attach to Instrument object in init
- Simple way precalculates 10K - 100K points upon instantiation, though many times they won't be used. Better if the functions generate the numbers upon first call
- Functions should refill themselves when empty
- Need support to provide seeds - make them options to Instrument object. One seed probably enough.
- To make things convenient, provide options for range and amplitude

[jklenzing]

Given the recent path in development, how should we best implement this? Should we still be implementing this?

[aburrell]

@rstoneback could you provide more background as to why this is desirable? That would help inform our actions.