3.1.12  Release 4.0.1

Version 2011-09-03-12.42.31.

This is a minor release.

The main user-visible change is that most major integer types have been renamed in anticipation of future support for 64-bit implementations:

    int31  -> tagged_int
    unt31  -> tagged_unt

    int32  -> one_word_int
    unt32  -> one_word_unt

    int64  -> two_word_int
    unt64  -> two_word_unt

The general pattern is that int types are now named in terms of their length in machine words rather than in terms of their length in bits: one_word_int will be 32 bits on 32-bit architectures but 64 bits on 64-bit architectures.