Template:User Language syntax enhancements

• Double quotation marks for quoted strings
• At sign (@) on right side of assignment
• Is Defined and Is Visible tests
• Copy qualifier for subroutine parameters
• Group field presence tests
• Normal syntax for LOB fields
• Implicit concatenation
• Relative values for Model 204 numeric parameters
• Longstrings
• Unicode
• Mixed-case User Language
• User Language Macro Facility
• External Call support for Stringlists and $lists