api: add into
api: into works given type as first argument
data: into
data: potential columns attribute on data descriptors
into: DataFrame <- DataDescriptor
into: DataFrame <- DyND
api: discover(DataFrame)
make blaze.dispatch

blaze.dispatch.namespace = datashape.dispatch.namespace
into: add failing test for nd.array <- DataFrame

Maybe @mwiebe can implement this well
data: chunks is lazy

It wasn't before.  This was a bug
csv: hints -> typehints
into: spark
into: restrict nd/np.array implementations

These used to support all objects, this raised ambiguities
into implementation DataFrame -> nd.array
Merge pull request #1 from mwiebe/into

Implement into for DataShape -> nd.array
into: add DataFrame <- CSV
into: rename spark test to avoid being tested
Merge pull request #336 from mrocklin/into

Add `into` operation to api