Allow Processing Rules to parse and set parsed values

Allow Processing Rules to parse and set parsed values.

Similar to what the St. Bernard tool does, allow processing rules to parse a delimited value and set the parsed value into another variable (regular or context).

Example 1: For xxxx_yy_zzzzz, look for the value between the first and second underscore and set that value into prop1. Result: prop1 = yy.

Example 2: For xxxx_yy_zzzzz, look for the value from the beginning of the string until the second underscore and set that value into prop1. Result: prop1 = xxxx_yy.

Yes, basically its regular expressions.