Update txtGallery and flatGallery to operate incrementally

Incrementally write a file instead of accumulating all lines of a text
file, then outputting them in the destructor. This avoids maintaining a
full copy of all metadata being written to disk.

ALso, respect readBlockSize in these galleries when reading incrementally.
Read bee format galleries row by row instead of as a single blob

For sufficiently large matrices, reading as a single blob will fail
Update binFormat to write its matrix incrementally

For sufficiently large matrices, attempting to write out a single blob
will fail.
Merge pull request #190 from biometrics/large_galleries

Better support for dealing with large galleries