Add directory import method.
Reorganize import and rename BaxterObjectView.

BaxterObjectView has been renamed to BaxterExperiment, to reflect its
purpose of providing an easy interface with other modules to carry out
image segmentation. The mass import_images() method was moved over to
BaxterExperiment accordingly.
Add command line parser.

The Baxter algorithm will be able to use BaxterExperiment by itself, but
this allows for more convenient post-hoc analysis.