fix possible ambiguity in do-bfs clauses
add non-colon versions of init and init-queue in do-bfs
clean up do-bfs code
fix possible ambiguity in do-dfs clauses

- non-backwards-compatible change: some do-dfs clause have an extra colon
bump to version 0.3
update doc for updated do-bfs and do-dfs
add history colon keyword history notes in doc