Wrote first version of non-symbol expectation-evaluating function, completely untested.  Also fixed a couple typos in distribution.py.

Still need to test alternate input versions.

calcExpectations now tested on more advanced cases.  Fixed dumb typo (copy-pasted from other line) and changed colons to ellipses in axis-construction step.

Also wrote new version of ConsAggShock solver that uses calcExpectation, as a demonstration of what the code would look like.

calcExpectation now correctly handles passing a null argument (empty list) for values, representing a function with no deterministic arguments.

dstn is now first

…Expectation