proposal to rename scrolling directions up/down as forward/backward [was: scroll-*-aggressively]

[Drew Adams]

> BTW, I think we should replace ye olde "scroll-up" and "scroll-down"
> terminology with "scroll-forward" and "scroll-backward".

1+

In principle, forward/backward has the same problem as up/down (ambiguous,
depending on what is considered to be moving), but in practice it does not.  

In Emacs, forward/backward generally refers to direction of movement through the
buffer.  The `scroll-up' doc refers to scrolling direction of the text/buffer
movement relative to the view, whereas many users think in terms of window (view
port) movement along the buffer (forward and down).

Renaming the commands to use forward/backward will help for this reason alone
(users think of forward as movement through the text/buffer).

Not sure what the best way of making such a change is, however.  In any case, we
no longer bind `scroll-up' - we bind `scroll-up-command' instead.  I just filed
a doc bug (#8349) about this.

Renaming the commands will no doubt help, but many users will never pay
attention to the command names.  They will use `C-h k' and look at the doc, so
it is especially the doc that needs to be clear.  (It is currently clear and
correct, but users can still become confused by the terminology.)