Runs a custom executable as a build step. The executable can be one defined by another build step, or a prebuilt executable.
The executable will be run if the outputfile is out of date (with respect to the input file or executable) or if it is missing.
Exec( alias ) ; (optional) Alias
{
.ExecExecutable ; Executable to run
.ExecInput ; Input file to pass to executable
.ExecOutput ; Output file generated by executable
.ExecArguments ; (optional) Arguments to pass to executable
.ExecWorkingDir ; (optional) Working dir to set for executable
}