Small: alternate drawDiscrete

[mnwhite]

The drawDiscrete function in HARKsimulation should be extended with a boolean input to choose between two modes:

1. Current implementation, where draws from a discrete distribution are independent of each other. Thus an input of p = [1/3,1/3,1/3] and x = [1,2,3] and N = 10000 might return an array of all 1's (with very small probability).

2. Alternate version that forces the simulated draws to match the discrete distribution as closely as possible, given the finite number of draws. A version of this is in ConsumerType.makeIncShkHist(), so not much new coding is required.

I think (1) should be the default, as that's how the other drawX functions work.

[mnwhite]

Done in new commit to comments-and-cleanup.