Converted BMPFormat

The loci.formats BMPReader has been converted to an ome.scifio.format:
BMPFormat. The legacy layer now delegates all functionality to SCIFIO.
Corrected SCIFIOFormatReader#getCurrentFile

This method now defers to the SCIFIO layer, instead of relying on a
legacy variable.
Added putImageMetadataList method

SCIFIO metadata can now map keys to lists of values.
Added Groupable interface

Both the Parser and Reader have a need to deal with muiltiple files.
Thus a new Groupable interface was added, with a common Abstract class
that both can extend, to avoid repeating this API.
wip: Dicom