Logix 500 Vines Per minute

[drbitboy]

I updated the code:

• Handle case where vines stop coming in, no vine limit switch rising edges occur, and the default rate calculate becomes stale. The new code now calculates a shadow rate as if a new vine is just coming in, and if that shadow rate is less then the last normal rate calculate, it publishes the shadow rate, which will decline until a new vine arrives.
• Refactored to move the XIC of the S:4/11 clock period trigger bit to the input map.

The published rate should likely be moved to an INT to allow for some rounding; 27.51234 vines/minute is not likely to be a practical or meaningful number to publish.