Roll Observatory packages and add a roll script

petitparser/lib/src/lisp/name.dart

-part of lisp;
-
-/**
- * An unique symbolic name.
- */
-class Name {
-
-  /** The interned symbols. */
-  static final Map<String, Name> _interned = new HashMap();
-
-  /** Factory for new symbol cells. */
-  factory Name(String name) {
-    return _interned.putIfAbsent(name, () => new Name._internal(name));
-  }
-
-  /** The name of the symbol. */
-  final String _name;
-
-  /** Internal constructor for symbol. */
-  Name._internal(this._name);
-
-  /** Returns the string representation of the symbolic name. */
-  String toString() => _name;
-}