Add max daily energy constraint for thermal_generator

[bknueven]

No description provided.

[darrylmelander]

Is this intended to be a limit per calendar day, or per 24 hour moving window?

[darrylmelander]

Also, what if the time horizon is less than 24 hours, like a SCED model with a 4 hour horizon? Should we allow the full energy budget to be used up in the shorter time frame or is there a better way to handle this?