- extra code injection prevention for script types
- add script_output type (return script results from stdout)

Via: https://forum.opnsense.org/index.php?topic=42.0

issue  https://github.com/opnsense/core/issues/63

Also style, license prettify, obvious bugs along the way.

Enables us to find all paths better using grep.  Always trying to
use the full path, even for system utility invoke in case those
move from ports to base or vice versa, related to #1.