In some cases, deserialize() can return a null object (if there were zero
input bytes).
In others, it cannot (for string or blob types).
Change the return type to optional<any> and adapt the deserialiation code
to deal with it.
Dynamic types come and go, so they need to be reference counted.
Switch data_type to using a shared_ptr<> for its implementation.
Since thread_ptr is not thread safe, the global primitive types must be
thread_local.
Simplistic database using std::map<> to hold rows, and boost::any to
hold values.
Supports:
- multiple key spaces
- multiple column families
- a few data types
Does not support:
- container data types
- secondary indexes
- composites
- validators
