PATCH: perlfunc cleanup, part 1

PATCH: perlfunc cleanup, part 1

So I started tidying up the C<delete> and C<each> documentation,
but ended up diddling the file pretty much all over.  There are
some typo corrections, but most of this is just smoothing out
infelicitous wording.  I did add one brief example to C<glob>.

I've made no warnings about delete and slices with negative
indices; I'm hoping that may be fixed, as David has suggested
be done.  It's not a political edit, just a copy-edit.

This is obviously only the first portion of the file, but the
tweaks were getting extensive enough I thought I'd better send
in a checkpoint.  I'll finish it up over the next several days.