Accepting alternative inputs for time steps

[sjordan29]

Initial implementation of pre-initializing timesteps takes a integer number of timesteps. We should expand this to include:

• Users to specify a timeseries (as a list?) to initialize the time dimension
• Users to provide a hotstart dataset that is pre-initialized on the time dimension. This would allow users to input a partially filled in hotstart dataset. The model would find the last populated timestep and use just that timestep onward moving forward to free up memory.

Others?