Done Support binary buffers in checksum functions

[Charles Dye]

@CKSUM[B,handle,offset,len]
@MD5[B,handle,offset,len]
@SHA1[B,handle,offset,len]
@SHA256[B,handle,offset,len]
@SHA256[B,handle,offset,len]
@SHA384[B,handle,offset,len]

• B: case determines case of the return value
• handle: as returned by @BALLOC
• offset: starting byte; optional, defaults to 0
• len: number of bytes to sum; optional, defaults to the remainder of the buffer