Move header files to include/djp.
Rename identifier -> id
Rename struct member decl -> classOrIntDecl.
Rename struct member decls -> classBodyDecls.
Add libdjp so clients can reuse the parser.
Update PackageDeclaration AST.
Rename token structures to our common pattern: tokKeyword.
Remove isEmpty() from Type.
Use 'pairs' to be consistent.
Use 'tok' var name.
Save comma positions in TypeArguments.
Keep names consistent.
Update PrimaryIdentifier to save pairs.
Update TypeList to use pairs.
Include position period when parsing CreatedName.