Populate new Pixels values in the 2013-06 schema
Change *PixelsBinDataBigEndian to populate/retrieve Pixels.BigEndian

This allows the correct attribute to be populated without having to
remove setPixelsBinDataBigEndian and getPixelsBinDataBigEndian (which
are used widely).
Parse magnification values as doubles

NominalMagnification is now an xsd:float in the schema, so it doesn't
make sense to parse and/or cast the magnification values to integers.
Add a MetadataOnly element

This replaces the BinData element that was previously created during
population of the "BigEndian" attribute.
Update type of NominalMagnification
Deltavision: fix magnification type
OME-XML: fix population of new Pixels attributes
Prevent duplicate IDs when populating OriginalMetadata XMLAnnotations

The previous code assumed that Annotation IDs started from 0; starting
from 1 or higher caused duplicate IDs to be used, which prevented the
XML from validating.
Only attempt to retrieve Annotation IDs if an Annotation exists
Fix endianness retrieval for older OME-XML files

Introduced in adb9503; getPixelsBinDataBigEndian now returns
Pixels.BigEndian if it exists, and BinData.BigEndian otherwise.  This
prevents isLittleEndian() incorrectly returning false because
Pixels.BigEndian may be null.
Merge pull request #597 from melissalinkert/2013-06-updates

Update OME-XML population to match 2013-06 changes