Draft "Unsafe fp optimizations" project description.

[Gabriel Dos_Reis]

| <<Yes, still we need to have a list of such supported plateforms; for
| future reference.
| >>
| 
| Well any platform could potentially use 64-bit arithmetic in place of
| 32-bit arithmetic, so I am not sure how you would limit the list for
| the second case.

Then, in that case the choice should be documented.

*Currently*, does that happen on -all- supported platforms?

-- Gaby