ND2: always set the field index to 2

This should fix plane ordering issues reported in
http://lists.openmicroscopy.org.uk/pipermail/ome-users/2014-March/004287.html
and QA 7983.
Merge pull request #989 from melissalinkert/nd2-field-order

ND2: always set the field index to 2
Update auto-generated documentation

Repository: openmicroscopy/bioformats
Already up-to-date.

Generated by BIOFORMATS-5.0-latest-docs-autogen#187 (http://ci.openmicroscopy.org/job/BIOFORMATS-5.0-latest-docs-autogen/187/)