Move hash_table_data into hash_table.hpp

svn path=/sandbox-branches/unordered-refactor/boost/unordered/; revision=41900
Only need a single templates 'hash_types' class.

svn path=/sandbox-branches/unordered-refactor/boost/unordered/; revision=41902
No need for hash_types to know about hash_table_data.

svn path=/sandbox-branches/unordered-refactor/boost/unordered/; revision=41903
Merge in changes from hash trunk. Most are in response to the review.

svn path=/sandbox-branches/unordered-refactor/boost/unordered/; revision=42111
Merge in changes.

svn path=/sandbox-branches/unordered-refactor/boost/unordered/; revision=42180