removed conditional checks for EPUB 2 only for processing NCX.

* In attempt to support EPUB 3 by testing with Moby Dick (EPUB 3 format), removed conditional checks for EPUB 2 for processing NCX global navigation data. Per the EPUB 3 spec, although not required, EPUB 3 epub containers should try and support NCX for foreword compatibility in older reading systems. The upside to this change is we can process EPUB 3 that have NCX, downside is EPUB 3 that do not will crash app. I can live with that for 1.0 but this needs to be fully addressed in a near term point release.

* commented out some fprintf debug statements