Performance enhancement for setting values

[mnblonsky]

Performance can be very slow when setting values of multiple elements because of the element order in OpenDSSDirect. It may be significantly faster to create a set_values() function that takes information for multiple elements and sets them in the optimal order.

Two possible options for implementation:

• Use class.First and class.Next and setting the values for each element as needed
• Save the OpenDSS order of elements for each class, then sort the elements of interest, then call set_() in that order