[R6RS] Renaming write-...

[Michael Sperber]

If we're renaming write-..., we should also consider renaming
read-... to get a matching pair (or at least avoid having a
non-matching one).  Choices:

1. display / read
2. put / get
3. output / input
4. out / in
5. push / pull

(I'm in favor of #2.)

Please also consider the names of `read' and `write', relating to
this.  (And the sound of pronouncing "xxx/xxx invariance.")  

1. read / write  (awkward with #1)
2. read-datum / write-datum (ditto)
3. <write-prefix>-datum / <read-prefix>-datum (for choices #2-#5)
4. <write-prefix> / <read-prefix>

(I'm in favor of #3.)

I'm also thinking these two should be in a separate library.

-- 
Cheers =8-} Mike
Friede, Völkerverständigung und überhaupt blabla