If a node has a List or Opt child, emit the type that parameterizes
the List of Opt.

This reverts commit 2ddfe66d.

This reverts commit 07db307a.

This reverts commit 1487f3bd.

This reverts commit d58c1c9f.

The Or node should represent a parsing alternative, while Seq nodes
are used to represent the application of a dotted-rule, which does
not have any semantic action.

Modify the methods that add or update children of an AST node to
return a reference to the AST node that is update (i.e. this).

The build did not work with Java 11 when using the Gradle wrapper because
Gradle 4.4.1 was used.  Updated the Gradle wrapper to use Gradle 4.10.3 which
supports building with Java 11.

The build will fail if the git submodule for tinytemplate is missing. This
updates the build script so that it gives an error message describing this
error rather than trying to build and causing lots of compile errors.

Wrong enclosing class reference was generated for dependency handlers in
attribute equations attached to subtypes.

Added new template variable used in attribute equation templates: HostClass,
a reference to the host class for the attribute equation.

fixes #307 (bitbucket)

Merge pull request #8 (bitbucket)

Inlined methods: Configuration.flushEnabled(), Configuration.flushAttr(),
Configuration.flushColl().

Use field of dependency node to access parameters fixing Java 6 compile error.

Algorithmic improvement from linear to constant (in number of attributes)
worst-case time complexity for dependency flushing.

This change replaces iteration over all attributes to flush attribute
dependency nodes by virtual method dispatch.  Previously, there were a series
of if-statements to check each attribute name against a dependency node's
attrID field. This has been replaced by using anonymous classes for dependency
nodes where a virtual method implements the correct dependency flushing
behaviour.

Removed flushing of NTA subtrees and dependency transferral.

Flushing NTA changes on dependency change is unnecessary work.

Removed commented-out debug code to clean up the template and generated code.

An NTA is never primitive or of type String.

Removed commented-out code to clean up aspect.

Added new attribute AttrDecl.isHOA() to tests if an attribute declared
as an NTA either in the aspect file or in the abstract grammar.

Removed commented-out debug code to clean up the template and generated code.

Extract method to prepare for larger refactoring.