Change to Default Value for SET MISSINGTEST

The MISSINGTEST parameter now has three values, OLD, SPECIAL, and NEW. The value NEW has been added and is the default value.

In prior releases, by default, when an IF-THEN-ELSE expression was used to calculate a result and the IF expression evaluated to zero (for numeric expressions) or blank (for alphanumeric expressions), the left hand side was checked to see if it had MISSING ON. If it did, and only some values were needed (NEEDS SOME), the result of the IF expression was MISSING, not true or false. The outcome returned was also MISSING, not the result of evaluating the THEN or ELSE expression. The SET MISSINGTEST = NEW command eliminates the missing test for the IF expression so that either the THEN expression or the ELSE expression will be evaluated and returned as the result. This is the new default behavior.