Refactoring the Type System

This pull requests is a rather large refactoring around the
type system. The source for this request is that we
currently support three basic types but with another three
types of dictionaries. To come to a point where we might
support any more we need to upgrade the system.

As a consequence I refactored the type system in the
following way. From the outside we have now 10 different
types:

  * INTEGER , FLOAT, STRING
  * [INTEGER | FLAOT | STRING]_MAIN
  * [INTEGER | FLAOT | STRING]_CONC
  * INTEGER_NO_DICT, FLOAT_NO_DICT

Depending on the type it is now possible to select the
correct dictionary, which can make casting easier.
Since we now now, that a column of type INTEGER_MAIN
is using an ordered dictionary. The mapping between
dictionaries and types is specified in
src/lib/storage/DictionaryFactory.h. At the same time
we define underlying types that allow the direct
storage. This means that INTEGER uses int64_t and so
does INTEGER_MAIN, INTEGER_CONC. This mapping is defined
in src/lib/storage/meta_storage.h. For fast plan
operations working on the direct storage this makes it
easier to distinguish which code paths to take. For
generic plan operations it is possible to verify if the
types are compatible using isCompatible(DataType,
DataType).

If you need to extract and upgrade / downgrade a
type use the helper functions specified in
src/lib/storage_types.h that allow you to
extract the ordered or unordered type.

To allow columns that can store their data type
directly within the 32bit of the value ID. I
added a new Dictionary called
PassThroughDictionary is acts like a cast and
does not store any state. It allows to
transparently integrate non dictionary columns
within the system. When Loading the data or
specifying columns use the INTEGER_NO_DICT
type string.

The ColumnMetadata object is no longer a pointer,
but is passed by value to avoid leaking and such.
Merge pull request #291 from hyrise/feature/simple_int_dictionary

WIP: Refactoring Type System