Move lib/dm-accepts_nested_attributes/model.rb -> data_mapper/nested_attributes/model.rb.
Define nested attributes methods in a module and include that.
Largely reworked, decomposed Resource responsibilities into 2 (main) new objects: Acceptor & Assignment.

Still need to go further. Especially w/r/t cleaning up and converting existing tests.
Decompose NestedAttributes::Relationship methods and tighten a few things up.
Add Acceptor::ManyToMany and move update & mark destroyable responsibilities from Assignment to Acceptor.

Eliminate DataMapper::NestedAttributes::Relationship and DataMapper::NestedAttributes::Relationship::ManyToMany, move responsibilities into Acceptor.

Assignment still talks a little too much to #acceptor.relationship, but not nearly as much as before, and conditionals are largely contained inside factory methods.
Move version.rb and bump version number (1.0.0 -> 1.1.0).
Pull key value extraction logic out of Acceptor into KeyValuesExtractor.
Clean up require statements and gemspec.
Rename a couple of queries for clarity (eg., negative to positive query).
Move resource updating logic into NestedAttributes::Updater.

Also synchronize and clean up #initialize interfaces of Assignment & Updater.
Eliminate need for Updater#relationship.
Clean up KeyValuesExtractor with Forwardable (a bit).
Eliminate a little duplication in Assignment#assign_new_resource.
Now all access to a relationship in Assignment and Updater happens through Acceptor.
Move new MiniTest specs to test/* to avoid false negatives in rspec runs.
Now all tests pass.
Improve output of Model#ancestors and backtraces from methods defined via module_eval.
Raise InvalidOptions on attempt to init Assignment::Guard with invalid value.
Version bump plus gemspec updates
Don't freeze the VERSION constant

Rubygems (at least on 1.9.2+) tries to #strip! the
string resulting in: can't modify frozen string