#11 Some MOOSE block parameters need discrete set of values

[Anna Wojtowicz]

The MOOSE Model Builder needs the ability to have parameters with a discrete set of values (defined in the YAML file).

This will probably happen in two steps:

• Anna - Parse YAML files so certain parameter Entries have their AllowedValueType set to Discrete, and the correct discrete values are added to the AllowedValues list. Examples to look at: RAVEN Component parameters > controlled, monitored
• Jordan - Enable MOOSE table viewer to have a drop-down field in the "values" column for parameter Entries marked as AllowedValueType.Discrete.

[Anna Wojtowicz]

This feature is enabled now, the properties table correctly renders a combo box for parameters marked with AllowedValueType.Discrete.