Add helper functionality and documentation

v0.2.1

Speaker class for human friendly node labels

v0.2.0

bump minor version

_bind_to_visitor AST method

Allows AST classes to create visitors that map to class constructors, so information about how to build a node can be centralized on the AST class object, rather than split between it and the visitor class.

AstNode class, with _from_fields method

Merge pull request #1 from datacamp/travis

Travis