Merge pull request #114 from mottosso/master

Updated API documentation and optional plug-ins (#92) implemented.
Improving API documentation and adding logo
Updating README
Improved href links in API docs
Instance('myname', parent=context) now adds instance to context
Improving cosmetics and adding lib.format_filename2
Improving API docs
Improving cosmetics in tests
Updating gitignore to not include _build from /docs
Updating logging logic
Fixes #115