Replace cooling coil model

[AntoineGautier]

This closes #2549.

[AntoineGautier]

Note that with the new cooling coil model, the models in Buildings/Examples/VAVReheat fail to simulate with JModelica. They have been excluded from the CI tests.

[JayHuLBL]

@AntoineGautier The changes are good to me, just need change back the .travis.yml.

[AntoineGautier]

TODO before merging:

• Update cooling FCU models in Buildings.Experimental.DHC.Loads with the new coil model

@JayHuLBL Sorry I forgot to update those models. This is done down. Could you please review the last commits?

[AntoineGautier]

@JayHuLBL This issue with OCT is fixed with d70513e.
I also added a start value for an iteration variable that the wet coil model introduces when configured in steady state, see 237bca2.
This is ready to merge if you are fine with those changes.

[JayHuLBL]

@AntoineGautier The changes look good to me.