features input

[perrygeo]

Introduces a click argument, features_in_arg, which utilizes a click callback to normalize the input of geojson features

Given the input:

• Path to file(s), each containing single FeatureCollection or Feature
• Coordinate pair(s) of the form "[0, 0]" or "0, 0" or "0 0"
• if not specified or '-', process STDIN stream containing
  • line-delimited features
  • ASCII Record Separator (0x1e) delimited features
  • FeatureCollection or Feature object

the features value will be a generator of GeoJSON Features.

Also add some docs changes

• More thorough usage example
• Enumerates the args and opts
• Removes deprecated plugins docs (reasoning: if it's deprecated, no need to clutter the main readme)

Test coverage is 100%, but design needs review and docs need work