v0.6.0-alpha

This release is a preview/alpha for pdfplumber v0.6.0. Among the more notable changes:

• Revamps the table-extraction methods, to simplify them and make them more flexible.
• Adds font size and font name to results of Page/utils.extract_words(...), based on @jsfenfen's suggestions in #28. (Thanks!)

Goals before v0.6.0-beta:

• Add Page.find_text_gutters feature, bringing back that table-finding strategy from earlier versions of pdfplumber.
• Attempt to fix/address as many extant GitHub issues as possible.
• Update the example notebooks, so that they work.

Goals before v0.6.0 full release:

• Reach full test coverage.
• Add more robust documentation.
• Add more/better docstrings.