Lemmings Revolution .BMP File format
  -Decompressed data represents a Windows Bitmap file

File
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ChunkNum        UInt8      The number of chunks in the file
Chunks          Chunk[]    The data chunks
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Chunk
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Header          ChunkHeader    Describes how the chunk is encoded
Data            Byte[]         The compressed input data
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ChunkHeader
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PackedSize      UInt16     The total size of this chunk, including the header
UnpackedSize    UInt16     The size of the data this chunk represents
(Unknown)       UInt8      Value of unknown significance; usually (always?) 4
RawTree         BinTree    Binary tree for raw byte counts
LengthTree      BinTree    Binary tree for distance/length lengths
DistanceTree    BinTree    Binary tree for distance/length distances
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BinTree
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The lower 4 bits of the first byte indicates how many additional values need
to be read from the input. If the value is 0, no additional input is needed
as the binary tree will not be used. If it's greater than 0, then add 2 to it
and read that many more values.

The values themselves are in 4-bit increments starting with the high bits of
the byte that contained the count, followed by however many bytes are
necessary to encode the remaining 4-bit values. For each byte, the lower 4 
bits are read first, followed by the higher 4 bits.

The last byte may have 4 bits of padding so that the next data begins on a
byte boundary.
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