Proposal: Introduce geo::GeoBuf struct, alter geo::Geo struct

[frewsxcv]

Idea

Currently, there exists just geo::Geo, which is a structure containing owned data. I propose we rename this to geo::GeoBuf and introduce a new structure containing borrowed data called geo::Geo. Table of similar analogies:

Owned	Borrowed
Vec	slice
String	str
PathBuf	Path
GeoBuf	Geo

Reasoning

Currently, if there exists a method centerpoint on Geo, and I want to apply this operation on a Wkt struct (from rust-wkt), I have to convert my Wkt struct to a Geo, and since Geo is owned, this results in memory allocations occurring.

With my proposal above, we would just need to interpret the Wkt struct as the new borrowed Geo, which results in a Geo struct that references the existing data in the Wkt struct, resulting in no new memory allocations.

Implementation

struct Geo will be renamed to struct GeoBuf

struct Geo will be a new struct with borrowed fields. Not too sure how this will look right now, but it's do-able.

Deref<Target=Geo> will be implemented on GeoBuf

[frewsxcv]

On second thought, I forgot that we have separate structs for each geometry type (e.g. MultiPoint, Point, etc.). Not sure how that would work...

[frewsxcv]

Another option here: https://gist.github.com/frewsxcv/1f334de4839fefc88a79

[frewsxcv]

This might no longer need to happen if #67 gets resolved.

[kylebarron]

Just curious, is there still interest in this? Is there a way today to use geo geometries from borrowed data? Or is the thought that in the long term geo traits will hopefully solve this use case?