Fixing alignment for base 1 positions. This replaces the corresponding paragraphs in Section 14.1 of draft 038.

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An element's representation is aligned to N units if P is the first position in the representation and P mod N = 1.  When parsing, the position of the first unit of the data stream is 1. 

For example, if alignment=4, and alignmentUnits='bytes', then the element's representation must begin at 1 or 1 plus a multiple of a 4 bytes.  I.e., 1, 5, 9, 13, 17 and so on.

The length of the alignment fill region is measured in bits. If alignmentUnits is ‘bytes’ then we multiply the alignment value by 8 to get the bit alignment, B. If the current position (first position after the end of the previous element) value is bit position N, then the length of the alignment fill region is the smallest non-negative integer L such that (L + N) mod B = 1.  The position of the first bit of the aligned element is P = L + N.