Add code to States to not interpolate if an exact solution exists (#374)

* Update format of range conversion coefficients isd output to include a separate list for times. Also update driver, test data, and remove unneeded semicolons

* Fix documentaion error

* fix other documentation error

* Add code to states to not interpolate if there is already an exact value for a time (solves divide by 0 error in interpolation code.)

* Updated to be more efficient

* lower_bound can also return the last elt. don't do that

* Added test for when no interpolation is needed for getState