Better support for non-zero lower bound arrays

[daniel . llorens]

This patchset adds better support for non-zero lower bound
arrays. Specifically, the functions sort, sort!,
restricted-vector-sort!, array-slice-for-each, and truncated-print from
(ice-9 pretty print) now support non-zero lower bound arrays.

The patchset also adds support for bitvectors in truncated-print and
completes the removal of uniform-vector-read!/write, which were still
present in the manual.

Finally, the patch installs the module (ice-9 arrays) with two (I think
rather obvious) functions, array-copy and typed-array-copy. This module
already existed in the tree, it just wasn't installed.

(ice-9 arrays) also includes two private functions, array-print-prefix
and array-print. These functions are meant to replace the C
implementation in arrays.c (scm_i_print_array), but I haven't completed
the replacement as the Guile version is about 3x slower in my
benchmarks. However, array-print-prefix is used internally by both
truncated-print and scm_i_print_array, and I believe that it will be
possible to make array-print faster in the future.

Regards

        Daniel