#39 se_tpb_filesetcreator: pageTarget/@value not always present

[James Pritchett]

If the contents of a pagenum in the dtbook document includes leading or trailing whitespace, filesetcreator will pass this through to the pageTarget in the NCX and, although calling it a "normal" page, will not include pageTarget/@value. It should probably trim whitespace when processing the content of pagenum's