Support for extremely large images

[aevitas]

As discussed in #2870 I am working with some very large images, and I'm running into some hardcoded limitations in ImageSharp, namely MemoryAllocator.MemoryGroupAllocationLimitBytes, which is currently set to 4GB.

Would it be possible to either make the maximum allocation size configurable through the Configuration, or adding some sort of mechanism to enable allocations of over 4GB?

[tocsoft]

you can configure/override this default via Configuration.

Configuration.MemoryAllocator = MemoryAllocator.Create(new MemoryAllocatorOptions {
    AllocationLimitMegabytes = 8000 // 8GB
});

[aevitas]

Fantastic, I don't know how I missed this. Thanks!

For completion, I updated the allocator of the Default configuration rather than creating a new configuration altogether:

    Configuration.Default.MemoryAllocator = MemoryAllocator.Create(new MemoryAllocatorOptions
    {
        AllocationLimitMegabytes = 8000
    });