CALC{"formula"} -- add spreadsheet calculations to tables

• The %CALC{"formula"}% variable is handled by the SpreadSheetPlugin. There are around 80 formulae, such as $ABS(), $EXACT(), $EXISTS(), $GET()/$SET(), $IF(), $LOG(), $LOWER(), $PERCENTILE(), $TIME(), $VALUE().
• Syntax: %CALC{"formula"}%
• Examples:
  • %CALC{"$SUM($ABOVE())"}% returns the sum of all cells above the current cell
  • %CALC{"$EXISTS(Web.SomeTopic)"}% returns 1 if the topic exists
  • %CALC{"$UPPER(Collaboration)"}% returns COLLABORATION
• Note: The CALC variable is handled with delay compared to other TWiki variables. You may get unexpected results if you nest CALC inside other variables (such as %INCLUDE{%CALC{...}%}%) because it does not get evaluated inside-out & left-to-right like ordinary TWiki variables. Use CALCULATE if you nest variables.
• Related: CALCULATE, IF, IfStatements, SpreadSheetPlugin