yeesian
maximum not always maximum
In this post: https://discourse.julialang.org/t/get-true-maximum-value-of-a-raster/70622/2
I found out that ArchGDAL.maximum, does not do any computation, and just returns the typemax if it is not in the metadata.
https://github.com/yeesian/ArchGDAL.jl/blob/8f4ace3d927e7f634927a5cb59c605bcbbdffda0/src/raster/rasterband.jl#L225-L231 https://github.com/JuliaGeo/GDAL.jl/blob/3838e938642712cf8a98c52df5937dcfdb19221e/src/GDAL.jl#L8631-L8647
The C API docs only say "Fetch the maximum value for this band.", but the C++ docs actually explains this: https://gdal.org/api/gdalrasterband_cpp.html#classGDALRasterBand_1a6021d86aca5668bd10e4e4f3f1967ce5
Right now we don't use pbSuccess, but perhaps we should. Don't know how though. We could optionally return it, such that users can check it if they want. In any case we should document this behavior.
