KDU is uploading 2k files with 7 and 8 layers which is shifting the location of discard 1 and 2.
To accommodate, this commit adds a max_layer check based on max_dimension and the MAX_BLOCK_SIZE to allow the extra layers for 2k.
Also shifted the starting size to the MIN_LAYER_SIZE instead of MAX_BLOCK_SIZE's area to allow smaller files to be decoded at discard 5 completely.
Finally able to walk around Fantasy Faire without any gray blobs!
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