revised motion #18 for July 19-20

[David Hough 754R work <754r@xxxxxxxxxxx>]

Revised to fit current draft:

Motion: Delete scaledprod operation from 7; add E.5. Scaled-product operations
 
Rationale:
The current specification is too limited to be worth standardizing.
Actual applications are just as likely to need over/underflow
protection for products of sums and differences.     And the array
versions would not likely be implemented upon a primitive with the prescribed
semantics (a more probable implementation primitive would return zero sf if
no over/underflow intervenes, and would leave sf undefined if there were
an invalid operation).    Since the whole point is performance,
the user feature (acting on arrays) would be implemented upon a performant
primitive.
 
So restore the actual user feature to annex E, which is where it came from
originally, as a means of avoiding specifying counting mode.
 
Text:
Delete scaledprod operation from 7.3.3 in the 754R draft.
Add E.5 Scaled-product operations by copying 5.3.2 Scaled-product operations
from http://754r.ucbtest.org/motions/archive/chapter5.pdf