GBB: fixes to select() and new select() tests. Reintroduces previous select()'s accidental compatibility with int ndarrays and marks this functionality as deprecated.

ENH: supports int ndarrays in the style of previous versions
DEP: throws deprecation warning if int ndarray code is used (+test)
BUG: python 3 produces a float index value because of '/' division when splitting the combined list in two - have changed this to '//'