actor/command line: Executes PROGRAM

Added

• Builtin symbol - string LINE_SEP
• Builtin symbol - string TAB

Changed

• Actor command-line - Executes a PROGRAM

Fixed

• Type files-matcher / matches -full - Crash rendering err msg for recursive model w too few files.
• Test - tests not working for CWD=/ or CWD=/sub
• Test - tests not working for Python >= 3.8 (comparison of XML-strings generated from objects with dicts)