CDK-177: Add FS deleteAll, finish tests.

This implements FileSystemView#deleteAll and finishes the FS tests. For
the getCoveringPartitions tests, it was necessary to compare FS views so
hashCode and equals methods have been added to AbstractRangeView and
MarkerRange. The AbstractRangeView implementations use the instance
class, so subclasses do not need to override them.
CDK-177: Rename View#in to View#of.

This commit renames View#in to View#of to avoid confusion with "in" as a
set-inclusion operation.