Added HasGeometryScropes trait and a sample implementation of within

[ajthinking]

Hi,
I was hoping to contribute to this repository. Could you please tell me if you like this structure?
If so I can add some more functions and make a test suite for them.

The scopes design is inspired from: https://github.com/grimzy/laravel-mysql-spatial/blob/master/src/Eloquent/SpatialTrait.php

I figured it would be nice to put these scopes in a separate file, or what do you think?

Also, pondered, what if scopes could accept strings like 'App\Park', tablenames, instance id or something else to make the actual queries inside of the database. To use the scopes with a WKT insertion does not seem optimal? Fine if it is some BBOX, but what if it has thousands of vertexes. Any guidance of these kind of questions would help alot.

Finally please be gentle as this is my first serious PR :)

[coveralls]

Coverage decreased (-0.7%) to 83.239% when pulling a1e1cdf on ajthinking:HasGeometryScopes into 16e77b8 on njbarrett:master.

[njbarrett]

HI @ajthinking - I think the style of the provided PR is fine, if you can write tests for it.
I actually think we need to allow you to scopeWithin another column of the database.
I am doing something similar on a seperate branch for a project where I needed this: https://github.com/njbarrett/laravel-postgis/blob/add-query-scopes/src/Eloquent/PostgisTrait.php#L79

However yours is a little more robust. So as long as its possible to reference a column as a point and a column as bounds then I would be happy with it.

[ajthinking]

Cool, I will get back here when tests are ready. And yes, I found that branch just as I wrapped up, but that was marked as stalled so I figured it was not to be merged (?).

I actually think we need to allow you to scopeWithin another column of the database.

Ill think about how that is done, ideally the parameter should support the geometry classes as well as other db columns. Will problably need some pointers from you or others. Can I use this PR and refresh it by commiting to my branch? Or should we do a new one?

[njbarrett]

You can keep committing to this branch.
And yeah the other branch I was working on for this wasnt intended for merging, just needed for a specific project but id like to get a robust solution in.