fs: code cleanup
samples: Support bzip in ReadNetCDF
dataset: Improve generic compareTo debug messages
graph: make CollectorVertex behavior the default

This patch adds traversal functionality for retrieving Path instances from a
collection of vertices and also provides vertex counts.

The old Vertex behavior (only one value, updates replace the value) can be
re-implemented in a child class; this is a better object hierarchy.
dataset: Remove unnecessary Feature value in base
Add production-ready reorientation capability.

This patch also includes improved debug messages for FeatureType mismatch
errors.
Add DOT format export capability.
Improve DOT export javadoc
bmp: add package-info for bitmap index package.