ccs2pcs: big renaming (ccsflat2pcsprelude + pcsprelude2pcs)
Also make distinguishing more restricted internal variants of the
formats more explicit (ccsflat, pcsprelude) -- this is known to
cause a little regression (format checking too strict to cope with
this) and the fix for that is forthcoming.
Signed-off-by: Jan Pokorný <jpokorny@redhat.com>