Allow NaN on limits for PI Vision 2021

We evaluate alarms that are not configured to NaN so that we can properly display alarm limits to the user for only the limits that are used. We upgraded to Pi Vision 2021 to correct an issue we found during one of our support cases for slow call-up performances when minimum/maximum limit traits were used. While the performance has been significantly improved to open the gauge element, the multi-state evaluation shows as "Bad Data" due to multistate limits attributes that evaluate to "NaN". In the previous version of Vision, "NaN" attributes were ignored and the color animation would display properly. We set up our templates in this fashion because we automatically pull alarm data points from our DCS as PI Points. That means we can dynamically update the alarm limits as alarms are added or removed. Not all transmitters have low, low low, high, high high alarms and sometimes it only matters if the high alarms are displayed as an example. It doesn't make sense to have to arbitrarily set low alarm limits so that the value will display properly. It can also be beneficial when alarms are added, so that they would automatically have their new alarm setpoints set and you wouldn't have to make any changes to the graphic to pick up new alarm setpoints.