Add GeoJSON type constants

[gabplch]

No description provided.

[jmikola]

Thanks for the contribution. I'll look into the CI failure (related to my Scrutinizer CI account) when I get a chance and get this PR merged/released.

This would be a good use of enums; however, the install stats still show a significant number of pre-8.1 users so I don't think it'd be worth bumping for that reason alone.

[gabplch]

What about the enums, I don't really think, that it is the place, where is is really needed.

[jmikola]

What about the enums

A defined set of constants would be a fine case for a backed enum; however, I don't think it's worth bumping the language requirement of the package. Happy to keep things as they are in this PR.

[gabplch]

Would you like to add more checks like phpstan/phpcs or others?

And when will you create new release?) I need it on my current project ^)

[jmikola]

I fixed the Scrutinizer issue. Please remove the order imports commit (3b3d4fb) from this PR and I can proceed with merging. I'm not sure why that was added but I'm not interested in those changes and prefer to keep use statements for classes and functions grouped separately.

[gabplch]

done

[jmikola]

Lost track of this after merging but I just tagged 1.2.0, which includes this and #45.