Chen model version
Added addStatesAsOutputs

A helper function that adds one output for each state in the model
Fixed a bug in accumulateFwd*

In the new accumulate functions, delta was not being applied on forward integrations.
Dimension 0 compartments now must be size 1
Experimental dosing feature

Only simulation with dosing works in this commit. Minimal testing has been done. Fitting and other higher-order functions to be added later.
Get rid of parfor

The defaults on Matlab's parallel toolbox result in a slower performance
rather than faster. If someone really needs speed, he can manually add
the parfor back in.
Dosing sensitivities

All the functions requiring sensitivities have been updated to
incorporate dosing as described in issue #7. This includes fitting. Left
out is LNA and MFK which never get love and curvature-requiring
functions, which are broken for other reason (#9).