Added subclass `TermValueArray` of numpy.ndarray that handles the pretty-printing of typical vsm data structures. Updated `*similar_*` functions to use it
Added `map_strarr` function, which generalizes the application of int->term maps to term-value arrays.
Collapsed `topic`, `print_topic` and `print_topics` to `topics`; `doc_topics` and `print_doc_topics` to `doc_topics` (using TermValueArray).
`LDAGibbsViewer.word_topics` now outputs an `IndexedValueArray`. Bug fixes to `IndexedValueArray` (was `TermValueArray`).
Added generic functions to make `*term*` and `*doc*` methods polymorphic about their input types. Added `sorted_topics` method. Replaces `relevant_topics`.