0.6.3

Converted all internal computations to use Float64 instead of Float32 thanks to @ffreyer's work in Makie.jl v0.21.
- Consequently, the PROJ_RESCALE_FACTOR hack is also removed.
- Zooming in close should also work now, with the correct ticks being shown.
Added the option to provide an integer scale in coastlines and land, which triggers GeoMakie to get data from NaturalEarth.jl instead of using the bundled data.
Updated the to_multipoly function to use GeoInterface traits, so that it's more universal.
Added several new examples - tissot.jl, source_crs.jl, etc.

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