Add AlternateOrder, TopRange and Range classes

[escowles]

The works extension includes a few classes that represent ordering and alternate structures:

• AlternateOrder: an alternate ordering of its parent's members. It should only order the parent's members, and otherwise has all of the features of ordering (some members may be omitted from the order, members may appear more than once in the order, etc.)
• TopRange: logical ordering of the component parts of an object, corresponding to a IIIF Range with the "top" viewing hint
• Range: a section of a Work, corresponding to a IIIF Range

These classes were added to support multiple orders and "logical order" (such as a Table of Contents or other overlay on top of the primary structure of an Object).

Should we add the AlternateOrder, TopRange, and Range classes to the core ontology?

See #53 for preliminary discussion.

[ruebot]

Summary of Islandora perspective:

• Fine with it, if we're not forced to use it.