Made some more progress on laying out productions. Moved some stuff around to make it easier to generate wrappers.

m lib/schemaform/adapters/generic_sql/adapter.rb
m lib/schemaform/adapters/generic_sql/wrappers.rb
m lib/schemaform/adapters/generic_sql/wrappers/model.rb
+ lib/schemaform/adapters/generic_sql/wrappers/placeholders.rb
m lib/schemaform/adapters/generic_sql/wrappers/productions.rb
m lib/schemaform/language/placeholders/entity_tuple.rb
m lib/schemaform/language/placeholders/placeholder.rb
m lib/schemaform/language/productions.rb

Started building generation support for derived attributes. Moved the Language::Placeholder tree into its own namespace to simplify wrapping.

m lib/schemaform/adapters/generic_sql/wrappers.rb
m lib/schemaform/adapters/generic_sql/wrappers/model.rb
m lib/schemaform/adapters/generic_sql/wrappers/productions.rb
m lib/schemaform/language/formula_capture.rb
m lib/schemaform/language/formula_definition.rb
+ lib/schemaform/language/placeholders.rb
m lib/schemaform/language/placeholders/attribute.rb
m lib/schemaform/language/placeholders/entity.rb
m lib/schemaform/language/placeholders/entity_tuple.rb
m lib/schemaform/language/placeholders/literal_list.rb
m lib/schemaform/language/placeholders/literal_scalar.rb
m lib/schemaform/language/placeholders/literal_set.rb
m lib/schemaform/language/placeholders/parameter.rb
m lib/schemaform/language/placeholders/placeholder.rb
m lib/schemaform/language/placeholders/tuple.rb
m lib/schemaform/language/schema_definition.rb

Improved production output formatting.

m lib/schemaform/language/placeholder.rb

Updated readme.

m README.markdown

Added present marker for optional attributes.

m lib/schemaform/adapters/generic_sql/adapter.rb
m lib/schemaform/adapters/generic_sql/wrappers/model.rb

Fixed a bug in Production conversion.

m lib/schemaform/adapters/generic_sql/wrappers/model.rb
m lib/schemaform/language/formula_capture.rb
m lib/schemaform/language/formula_definition.rb
m lib/schemaform/language/placeholder.rb
m lib/schemaform/language/productions.rb

Added list generation.

m lib/schemaform/adapters/generic_sql/wrappers/model.rb

Added set generation.

m lib/schemaform/adapters/generic_sql/wrappers/model.rb

Added code to prevent inherited attributes from being re-generated during layout.

m lib/schemaform/adapters/generic_sql/wrappers/model.rb

Lay out code has been merged into the wrappers.

- lib/schemaform/adapters/generic_sql/lay_out.rb