Higher level types for Values and DataArrays

[gicmo]

Currently we only support 'primitive' types, e.g. everything that is in the DataType. How should we handle more complex times like:

• DateTimes (needs storage type and interpretation, e.g. int as seconds since Epoch, string as ISO 8601)
• Complex Numbers
• Images (encoding, format, ...)

[achilleas-k]

Well, one thing I've been hoping for is to drop boost as a dependency completely. Not sure how I feel about adding more back in.

[gicmo]

@achilleas-k yeah, should be done without libboost dep.