select-rows implemented
tests for select-rows
select-rows protocol added
select-rows reimplemented
select-rows works only on seq of indexes
row-maps moved to protocol implementation
dataset constructor from columns names and row maps added
tests for new dataset constructor added
typo in dataset tests fixed
select-rows reimplemented using dataset-from-row-maps constructor
dataset constructor accepts seq of rows instead of seq of columns
Merge branch 'select_rows' into develop

Conflicts:
	src/main/clojure/clojure/core/matrix/impl/dataset.clj