NRRD: defer helper reader initialization

Instead of initializing the helper reader in setId (where we don't need
it), wait until openBytes is called for the first time.
Andor SIF: reduce the number of readLine() calls

This brings the setId time down to ~0.5s.
Varian: reduce the number of calls to readLine()

This brings the setId time under 0.5s.
Molecular Imaging: reduce the number of readLine() calls

setId time is now under 1s.
Zeiss CZI: reduce setId time for files with uncompressed images
InCell: setId performance improvements

In particular, reduce the number of loops over core.size(), and the
number of objects instantiated in said loops.
Leica LEI: improve setId performance

This primarily involves reading the entire .lei file into memory and
only calling list() when absolutely necessary.
Operetta: reduce setId execution time
CellWorX: minor setId performance improvements
CellR: reduce setId execution time
Canon RAW: reduce setId execution time
Leica: throw a nicer exception if TIFF files are not found
FakeReader: remove pointless comments

For some reason Eclipse adds these sorts of comments, but a simple
Ctrl+T in Eclipse (and similar functionality in other IDEs) will give
you the same information and more in an instant.
FakeReader: change shadowed variable name
FakeReader: remove empty, undocumented block

This avoids an Eclipse warning.
Migrate XMLMockObjects from OMERO codebase

This class stands alone from the OMERO clients, and is very useful for
generating various OME-XML blocks for testing, so it fits nicely with
the rest of the OME-XML Java library.
FakeReader: add support for generating SPW data

This implementation leans on XMLMockObjects, and is largely untested.
Remove debugging statement
CellR: fix path name tokenization on Windows

Noticed by Findbugs.
Update repositories blocks to be consistent

The rest of the POMs use maven.imagej.net, so that's what we use in
loci-common and scifio-devel now, too.