Facade/Free-field at plant

[goodhandd]

This is secondary to "facade/free-field at receptor" new feature.

There needs to be a selector button for each plant where you can select "facade" or "free-field". The button needs to be the very first thing after the slider where you select the plant noise level. The default needs to be "free-field" and sends 0 dB as a variable to the model. If "facade" is selected then it needs to send 3 dB. I already have a function in there that will add this to the noise level at receptor. I will probably need to add a few lines of code to get it working.