Lean AST is built.

An AST is built by parsing a test specification and using the Gherkin
event API for each node of the specification. This information is then
passed to a runner that builds RSpec execution block based on the nodes.
Steps execution indicates non-existing steps.

As an initial attempt at execution, the first stage is having the
framework report that the actual steps found in the test spec do
not exist. Currently this is a hard-coded exception that occurs
any time a step is executed.
A DSL for the "lean" lucid is exposed.

The lean version of Lucid will not require matchers to refer to Given,
When, or Then as method names. Instead, all matchers will be referred
to via a "step" method. This allows for test definition files to
provide a top-level step method.
Removal of lean lucid approach.