Add a warmup flag as a built in variable to EMS

[JasonGlazer]

Some dynamic controls that would be simulated in EMS (especially those based on using random numbers) cause convergence errors in if they are part of the warmup period. Adding a flag variable to indicate when warmup is happening would allow EMS controls to behave in a simpler way during warmup and possibly avoid convergence errors.

[EnergyArchmage]

I can take this one. 2 second job.

[JasonGlazer]

Can you think of any other EnergyPlus internal variables that would make sense to expose to EMS users?

[EnergyArchmage]

completed this and made a pull request on branch 4743-EMS-warmup-flag. I don't know what to do with the word doc snippet that accompanys code change.

[JasonGlazer]

Docs go in:

https://github.com/NREL/EnergyPlusBuildSupport/tree/master/docs/src/mods/for_2015_03_release

[Myoldmopar]

Closed with #4743