[WIP] updates to cstwMPC for 0.10.6

[sbenthall]

This PR attempts to update the cstwMPC code to bring it in line with recent changes to HARK core libraries.

I got hung up at around line 275 as I'm not sure what this code is doing:

https://github.com/econ-ark/HARK/blob/master/HARK/cstwMPC/cstwMPC.py#L270-L281

[sbenthall]

Stack trace for this issue:

Traceback (most recent call last):
  File "cstwMPC.py", line 622, in <module>
    main()
  File "cstwMPC.py", line 604, in main
    center_estimate = brentq(paramPointObjective,param_range[0],param_range[1],xtol=1e-6)
  File "/home/sb/.virtualenvs/econ-ark/lib/python3.7/site-packages/scipy-1.3.1-py3.7-linux-x86_64.egg/scipy/optimize/zeros.py", line 775, in brentq
    r = _zeros._brentq(f, a, b, xtol, rtol, maxiter, args, full_output, disp)
  File "cstwMPC.py", line 602, in <lambda>
    dist_type = Params.dist_type)
  File "cstwMPC.py", line 412, in getKYratioDifference
    Economy.distributeParams(param_name,param_count,center,spread,dist_type) # Distribute parameters
  File "cstwMPC.py", line 277, in distributeParams
    self.agents[j](AgentCount = int(self.Population*param_dist[0][b]*self.TypeWeight[n]))
TypeError: 'DiscreteDistribution' object is not subscriptable

[sbenthall]

Closing this. cstwMPC will be removed soon.