client interface for Optic enhancements

[ehennum]

The enhancements are as follows.

fromSearch() accessor
fromSearchDocs() convenience

groupByUnion() and groupToArrays() modifiers
facetBy() convenience
group(), rollup(), cube(), and namedGroup() helpers
hasGroupKey() aggregate

bind-as() modifier

in() operator

[ehennum]

Includes unit tests

JavaDoc for new manually maintained interfaces still todo

[ehennum]

The latest commit (4634719) relaxes a limitation in that getString() now supports anything other than a binary node.

Previously, getString() only supported atomic values.

Thus, negative testing that confirms the limitation might start failing.