Scriptconfig

Changed
* Config.load can now handle aliased input.

Fixed
* Fixed bug where argparse attributes were sometimes dropped.

Changed
* Added a metaclass to DataConfig, which means calling the decorator is no longer necessary.

Fixed
* Added workaround for issue with pickle-ability

Added
* New method: `to_omegaconf`
* Experimental `dataconf` and `DataConfig`

Changed
* Can now pass cmdline as a kwargs dict.
* Added support for `required=True`

Fixed
* Issue with custom parsers and tracking "explicitly given"

Changed
* Added type information
* Doc improvements

Added
* `smartcast` can now disable splitting by specifying `allow_split=False`
* Broken: Added `required` as an option to `Value`.

* The `short_alias` keyword to `Value`, which allows single '-' prefix chars on
the command line.

* The `port_argparse` method which takes an existing (simple) argparse CLI and
attempts to make a scriptconfig version of it.

Changed
* The `alias` keyword no expands a single argparse argument instead of making
multiple of them.
* Make numpy optional