Data.String: bugfix typo in common_head()
Data.String: bugfix in diffidx()

bugfix double return and call strlen()
around common_head().
Merge pull request #85 from deris/bugfix/common_head

Data.String: bugfix typo in common_head()
Merge pull request #86 from deris/bugfix/diffidx

Data.String: bugfix in diffidx()
Data.String: rename: %s/replace_once/replace_first/g
Data.String: changelog for the rename: "replace_once() -> replace_first()"
DateTime: better english
DateTime: add TODO
Text.Lexer: fixed document
Text.Lexer: fix typos in doc
Text.Lexer: update document