Fourth Draft "Unsafe fp optimizations" project description.

[dewar@gnat.com]

<<Provided that the warning is never added to -Wall, and provided that the
text is changed (for example, to "may be unsafe", which is more accurate),
it's OK with me.  It may be useful to request the compiler to flag these
operations.
>>

OK, I agree, that's OK with me to (leave it under its own special flag,
and change the warning to say "may be" :-)