Implemented support for the PBS/Torque Parallel Execution Environment.
The PBS/Torque support now handles the IF-EXISTS argument like PREPARE-OGE-SCRIPT.
The PBS/Torque support now handles an ERROR argument like PREPARE-OGE-SCRIPT.
Made IF-EXISTS argument to PREPARE-XARGS-SCRIPT behave like the other script generating functions.
Updated documentation on the parallel execution environments for the Oracle Grid Engine, xargs(1) and PBS/Torque (new).
Added todo item to add OUTPUT and ERROR arguments to PREPARE-XARGS-SCRIPT.