Peter M. Groen / openbr

Better support for dealing with large galleries

For sufficiently large matrices, attempting to write out a single blob
will fail.

For sufficiently large matrices, reading as a single blob will fail

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.

Address #188 (gallery names not propagated to mtxOutput)

Remove NoneTransform, it is a strict duplicate of IdentityTransform

This avoids warnings about project(file,file) shadowing
project(template,template).

Introduce transforms which operate solely on metadata

Stream based comparison

Also, minor stylistic/clarity tweaks for cascade training

Introduces MetadataTransform and UntrainableMetadataTransform, which
provide a project(file,file) interface for defining operations that only
affect metadata, and do not touch matrices.

Modify a number of transforms to inherit from these interfaces instead of
UntrainableTransform or UntrainableMetaTransform

Instead, we just prepend/append to transform lists as needed. Maybe this
is less confusing.

Move emptyRead to a higher visibility scope, and make it handle caching
metadata in addition to reading galleries. Caching still leverages
memGallery since re-implementing a cache just for FileLists would largely
be redundant.

generalized -evalDetection

Split downloading the MEDS dataset to a separate file

downloading all the datasets in downloadDatasets.sh is time consuming, and
MEDS is the only dataset used in make test, as well as
evalFaceRecognition-MEDS.sh. Splitting MEDS to a searate file simplifies
the process of validating an OpenBR build.

Added training for cascade classifiers