validate direction number degree in SobolSequenceGenerator stream parser

[dxbjavid]

SobolSequenceGenerator.initFromStream reads a per-dimension degree s from the direction-number stream passed to the public SobolSequenceGenerator(int, InputStream) constructor, then allocates new int[s + 1] and writes direction[d][1..s] even though each direction[d] holds only BITS + 1 entries. A line with s > BITS throws a raw ArrayIndexOutOfBoundsException and s < 1 throws NegativeArraySizeException, instead of the MathParseException this parser uses for every other malformed line. Reject out-of-range s before the allocation so bad input maps to MathParseException like the surrounding token parsing.

[aherbert]

Thanks for the bug fix. Can you add a unit test that fails without the patch. Thank you.

[dxbjavid]

Added testConstructorDegreeTooLarge. It feeds a stream with degree s=60 (BITS is 52), which hits a raw ArrayIndexOutOfBoundsException without the patch and now gives MathParseException.