Guarantee dependency isolation. Improvements to HTMLTagSplitter and HeaderSplitter

v0.6.5

Features

• Add a util class to convert HTML to Markdown content.
• Improve Header Splitter to always return its content in markdown format.
• Add the option to return text in markdown format for HTMLTagSplitter.
• Add the option to batch content when using HTMLTagSplitter: If batch=True, it returns the chunks grouped by tags up to the numbers of characters specified by chunk_size. If False, it will return one register per tag.

Bug fixes

• Dependency isolation was not guaranteed: implement safe lazy imports in all the init methods.
• Raise test coverage up to 90%.