Implement rvars across all sub-components and components

[rburghol]

The default implementation had 2 variables to track inputs and outputs from sub-components:

• vars A list of all variables either read by this object (i.e. arguments in an equation) or written by this object on the parent.
• wvars: A list of variables written by this object on the parent.

There is a note in the source code in the base modelObject class in orderOperations() (see) that:

//       @todo: rvars on subcomps are explicit independent inputs to subcomps that are not yet handled
//        wvars are explicit outputs from subcomps that are often used by other comps
...

Some objecdts have begun to implement this, such as hydroImpSmall, but most others do not. For example: after the line $this->vars[] = $thisop; in the Equation class we should add $this->rvars[] = $thisop; to make the rvars a valid indicator of required inputs (see Code 1 below). We need to:

• Insure that all sub-comps handle rvars separately in their parseOperands or other init() steps.
• Special handling for DataMatrix (see Make variables in DataMatrix columns part of orderOperations() sorting #378)

Code 1: The parseOperands() function in class Equation (see code here).

   function parseOperands() {
      $ops = array();
      $arOperands = preg_split('/[\)\(\+\-\*\/\\^]/',$this->equation);
      foreach ($arOperands as $thisop) {
         $thisop = ltrim(rtrim($thisop));
         if (!is_numeric($thisop) and (strlen($thisop) > 0)) {
            # not numeric, must be a variable, not a constant
            # check to see if it has been added already
            if (!in_array($thisop, $this->vars)) {
               $this->vars[] = $thisop;
            }
         }
      }
   }