Yirgacheffe 2.0

[mdales]

Addresses #38, #70.

Added

• Added a dimensions property to layers to give the raster equivalent width and height.
• Added an as_area operator to redefine the area of a layer for use in a calculation. Useful for overriding the default behaviour of operators in terms of the area they take, and for explicit clipping or padding of inputs.
• Added an as_projection operator to reproject a raster or calculation to a new map projection.
• Added h3_tile to generate a layer for rasterizing H3 tiles.

Changed

• Moved find_intersection and find_union to top level of module.
• Renamed map_projection to projection.
• Vector rasterisation has performance improvements.
• Renamed astype to as_type to match similar Yirgacheffe operators for area and projection.

Fixed

• Fixed a tessellation issue with H3 tiles overlaying each other when summed.

Removed

• Removed mutable layer properties set_window_for_intersection, set_window_for_union, offset_window_by_pixels, and reset_window. Use the immutable as_area operator instead.
• Removed window property from the public API.
• Removed Window class from the public API.
• Removed PixelScale class, deprecated for a long time, use MapProjection instead.
• Removed RasteredVectorLayer class (use VectorLayer instead).
• Removed old projection and pixel_size properties from layers that are now combined in the MapProjection object.
• Removed layers from the public API, core methods (e.g., read_raster, read_shape) or operators (e.g., as_projection) should be used to access layers instead.
• Removed properties from internal LayerObject API that was earlier exposed and had to be maintained for backwards compatibility.
• Remove WGS_84_PROJECTION constant - for a while now this has been deprecated since we added more human readable string support (e.g., "epsg:4326").
• Removed scaled_raster_from_raster which created an in memory rescaled image. Use read_raster_like to generate a dynamically scaled raster instead.
• Removed RescaledRasterLayer as it is superceeded by the ReprojectedRasterLayer which does both pixel scaling and map projection conversions.
• Removed numpy_apply and shader_apply operators, which was a backstop for lack of operators in early Yirgacheffe.
• Removed geo_transform from layer, as it duplicated the same function on the layer's area object.