partition, split, split*: iter used for indices

* lib.c (partition_func, split_func, split_star_func):
Indices passed through lazy cons are now iterator,
rather than a sequence accessed via car and cdr,
which is inefficient for nonlists.
(partition-split-common): Use iter-begin to convert
indices to iterator, which becomes the cdr field of
the lazy cons.

* txr.1: Update documentation for these functions to clarify
that the second argument is a sequence. The inaccurate
text claiming that "if the second argument is an atom
other than a function" is rewritten. This doesn't describe
the behavior that is implemented, where the test applied
is seqp, not atom. The indices can be a vector of integers,
which is an atom.

0 files changed, 0 insertions, 0 deletions