Adds --process-parts Option

This release adds the --process-parts option.

The --process-parts option extracts parts of a JCR file into multiple files based
on comments in the file. It can also create a new file without the
comments. This is useful for JCR going into specification documents
where it is nice to break the JCR up for illustrative purposes in
the specification but to also have one JCR file for programmatic
testing purposes.

The file parts are extracted using the comments

; start_part FILENAME

and

; end_part

The comments must also be the only thing present on the line
though leading whitespace is allowed if desired.

To get a new file with all parts but these comments, use this

; all_parts FILENAME