Rewritten parser for GeoJSON files to handle styling

[John Zaitseff]

Hi, everyone,

I tend to use the GeoJSON format (RFC7946) for storing things like
the routes taken on my motorcycle rides.  However, Marble currently
has incomplete support for this format: files can be loaded, but any
style formatting included by sites like https://geojson.io/ (and as
specified by the Simplestyle spec v1.1.0) is ignored.

To be honest, I found this lack of formatting rather annoying.  So
since I had a couple of free days, I've taken the liberty of
rewriting the GeoJSON runner plugin.  It now handles all valid
RFC-compliant files (including those without a top-level
FeatureCollection object and those with recursive GeometryCollection
objects -- these previously could not be loaded at all).  It also
handles most of the Simplestyle properties.

Could you please review the series of patches I'll be sending to
this list: I currently have ten lined up (using "git format-patch").
If you prefer, I can set up a publicly accessible Git repository on
my server from which you can do a pull -- I don't use Github.

This is the first time I'm sending patches to Marble, so I most
definitely expect I'll need to revise them!  Please let me know how
I should do so, and how I should adjust to your workflow.  Thanks!

Yours truly,

John Zaitseff

-- 
John Zaitseff                   ,--_|\    The ZAP Group
Telephone: +61 2 9643 7737     /      \   Sydney, Australia
Email: J.Zaitseff at zap.org.au   \_,--._*   https://www.zap.org.au/
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