IRIX 5.3 has no `long double'

[Brian Gough]

Nearly all the use of long double is through the template macros, so
it is fairly easy to bypass it by modifying the file templates_on.h. 

There are a handful of other cases that can be fixed with 

  s/long double/double/ 

none of which are essential but just are places where it is nice to
get some extra precision if it's available.

The long double type is part of the ansi standard, so the $64,000
question is: If the compiler doesn't support it and we work around
that will we get into problems with other non-ansism's?  If the
compiler builds the library cleanly after removing long double then it
would be reasonable to make it optional.

Steve ROBBINS writes:
 > 
 > ... at least, not in the vendor compiler.  I just made a quick attempt at
 > compiling the code (cvs update'd this evening) and it fails when using the
 > IRIX compiler, due to not having long doubles.
 > 
 > Is there any point in attempting to detect long double support?
 > Would the code work with all the long double types removed?
 > 
 > -smr
 > 
 > P.S.  GCC under IRIX 5.3 does support `long double's, so it is not a
 > complete disaster for us. 
 > 
 > 
 >