Enable use of TileDB from Julia (www.julialang.org).

Currently, all array dimensions must be of the same type. TileDB should support dimensions of different types as well.

TileDB should support attaching axes labels (dataframes in their full generality), so that the user can slice the array based on arbitrary axes label predicates.

TileDB currently performs only slicing. It should allow other computations, such as filters, group-by queries and joins. This will help high-level application push compute closer to storage.

This will enable TileDB to support fast out-of-core key-value queries. In addition, it will be able support ND and prefix string queries.

TileDB should support slicing with strides, which is quite common in numpy and similar tools.