Z and M dimension support

[evetion]

While going through #290, I noticed some issues with geometry types, especially the non-default ones with Z and/or M dimensions.

• Missing getm. (added in Implement new GeoInterface traits #290)
• Creation of geometries don't support m (four coordinates)
• Creation of geometries don't set correct type, createpoint(0,0) and createpoint(0,0,0) both result in ArchGDAL.IGeometry{ArchGDAL.wkbPoint}, while the latter should be wkbPoint25D or wkbPointM.

[yeesian]

how do we know whether createpoint(0,0,0) should be wkbPoint25D or wkbPointM?

[yeesian]

My implicit understanding was that createpoint(0,0,0) would have PointZ semantics, and PointM and Point25D are not supported in this package yet.

[rafaqz]

@yeesian I agree, regular arguments should be spatial dimensions. M could use a keyword argument.

[yeesian]

Does that mean

• createpoint(0,0) -> ArchGDAL.IGeometry{ArchGDAL.wkbPoint}
• createpoint(0,0,0) -> ArchGDAL.IGeometry{ArchGDAL.wkbPoint25D} (per https://gis.stackexchange.com/a/7869)
• createpoint(0,0,m=0) -> ArchGDAL.IGeometry{ArchGDAL. wkbPointM}
• createpoint(0,0,0,m=0) -> ArchGDAL.IGeometry{ArchGDAL.wkbPointZM}

?

[rafaqz]

Yeah, that would work. Otherwise just use a different function with m last.

[evetion]

Discussed is3d and ismeasured in #303, which are now implemented in #290. Methods to actually create/set these coordinates (especially for m) are still missing.