Require PEG only in the "parser" task -- it may not exist when executing
the "build" task. Also don't make the "build" task dependent on the
"parser" to break a dependency circle.
Or, swapped Ruby dependency for a Node dependency.
The build script was also modified to always regenerate the parser (in
case of the "parser" task) or rebuild the library (in case of the
"build" task) even if the source files were not modified. Not doing this
led to problems when the generating code changed but the files didn't
(which happened often during development).
David Majda