remove bogus cross-phase-persistent declaration

Also fix and improve source-location reporting.
raco pkg show: include only non-auto by default
adjust ".plt" S-expression matching to accept more old archives
quick: fixup for `slideshow' vs. `pict'
show package for each module in documentation

The package is normally determined automatcially, but
the `defmodule' form also supports a `#:packages' option.
fix `raco setup' package-dependency check when PLaneT package is installed