Access World's sorting ivar directly

Was getting "undefined method `show' for nil:NilClass (NoMethodError)"
in failed When step, with code "sorting.show"

Now getting "undefined method `show' for #<RecordParser::Sorting::ByGenderAndLastName:"
which is normal and expected.
Correct reference to test collaborator

Missed this in e6c795c: "fake_output" should now be called "out".
Separate specs and pass features

This commit separates the specs for RecordParser::Sorting::Base
into separate specs for RecordParser::Sorting::ByGenderAndLastName
and RecordParser::Sorting::ByLastNameDescending, adding code to
those classes to pass specs.  Features are passed in the process.
Move code to child classes
Simplify output by removing heading and blank line

Previously, the application output a blank line and a heading before
presenting the sorted records. Since the app is not interactive and
the method of sorting is chosen at execution, the heading is noisy
and not necessary.

This commit:
* Removes the heading from the sample output in feature scenarios.
* Removes specs that reinforce the heading behavior.
* Removes the code that produced the heading.
* Simplifies and combines spec setup.
Shorten Sorter method names
Simplify private method name
Collapse private methods