ProgramRun -- result of running an external program

A hash table returned by runProgram with the following strings as keys:

• "command", the command that was used to run the program.
• "output", the output of the program to stdout.
• "error", the output of the program to stderr.
• "return value", the return value of the program, possibly multiplied by 256 (see run). Note that this is what is displayed when printing a ProgramRun object.

In addition, if runProgram is called with the KeepFiles option set to true, then the following keys will be present:

• "output file", the path to a file containing the output of the program to stdout.
• "error file", the path to a file containing the output of the program to stderr.