Use the KWSys Process "MergeOutput" option to give the child process
the same pipe (or file) for both stdout and stderr. This allows
natural merging of stdout and stderr together instead of merging
on arbitrary buffered read boundaries as before.
State in the execute_process how COMMAND arguments are passed to
the child. Add a note at the end about how the command differs
from add_custom_*().
Suggested-by: Alan W. Irwin
Brad King
Kitware Robot