Support Fiona Input and Output

[justb4]

Fiona https://github.com/Toblerity/Fiona is a really nice framework to interact with OGR inputs and outputs. It also takes a Pythonistic approach in creating lightweight datastructures for Features (Python built-in types).

Integrating Fiona into Stetl should not be too hard:

• Input: create a Fiona Input Component that can Open an OGR source and supply a stream or list of Features
• FORMAT: add a new format fiona_record or something similar
• Output: create a Fiona Output Component that can Open an OGR source and write a stream or list of Features

Within Filters we may apply any other programming, like with Shapely.