Refined Zip logic, but no change in epubcheck results
Revert "Refined Zip logic, but no change in epubcheck results"

This reverts commit a2acc5eb7fed4279d77fad3a5d4d788f24d4de78.
Added zip64Mode='never' to zip for mimetype file. Requires ant 1.9.1+
Remove ncx namespace prefix
#27 Don't process maprefs for OPF output.