[Rd] print()ing of raw matrices (PR#7912)

[maechler at stat.math.ethz.ch]

Not a bug in a very strict sense, 
but still something to be fixed eventually:

> s <- sapply(0:7, function(i) rawShift(charToRaw("my text"),i))
> s

 ... nothing is printed at all

> str(s)
 raw [1:7, 1:8] 6d 79 20 74 ...
> c(s)
 [1] 6d 79 20 74 65 78 74 da f2 40 e8 ca f0 e8 b4 e4 80 d0 94 e0 d0 68 c8 00 a0
[26] 28 c0 a0 d0 90 00 40 50 80 40 a0 20 00 80 a0 00 80 40 40 00 00 40 00 00 80
[51] 80 00 00 80 00 00
>

and similar behavior for arrays, e.g.,

> dim(s) <- c(7,4,2)
> s
, , 1


, , 2