Allow grass curing, leaf-on/off, and other calculated conditions to be set manually

[jordan-evens]

Right now time of year and location is used for curing and green-up.

Should be able to override any and/or all calculated values with any of:

• a single value for entire run
• a start-up value to be used as the initial condition, and then use the existing equations to calculate the difference to change that by
• a list of individual values to be used hourly

[jordan-evens]

partially done - settings for entire simulation duration being constant exist

   --curing                  Specify static grass curing
   --force-greenup           Force green up for all fires
   --force-no-greenup        Force no green up for all fires