* Generate Reader and Writer methods which cache attribute values in hashes.  This is to avoid repeatedly parsing the same date or integer columns.
 * Move the attribute related methods out to attribute_methods.rb to de-clutter base.rb
 * Change exception raised when users use find with :select then try to access a skipped column.  Plugins could override missing_attribute() to lazily load the columns.
 * Move method definition to the class, instead of the instance
 * Always generate the readers, writers and predicate methods.


git-svn-id: http://svn-commit.rubyonrails.org/rails/trunk@7315 5ecf4fe2-1ee6-0310-87b1-e25e094e27de