Double-float operators

### Double-float operators

These `double-float` declared-numeric operators are defined in the `:gbbopen-tools` module:

 Operator Operation Example `\$\$` `the double-float` `(\$\$ x)` `+\$\$` `+` `(+\$\$ x y z)` `-\$\$` `-` `(-\$\$ x y z)` `1+\$\$` `1+` `(1+\$\$ x)` `1-\$\$` `1-` `(1-\$\$ x)` `*\$\$` `*` `(*\$\$ x y z)` `/\$\$` `/` `(/\$\$ x y z)` `=\$\$` `=` `(=\$\$ x y z)` `/=\$\$` `/=` `(/=\$\$ x y z)` `<\$\$` `<` `(<\$\$ x y z)` `<=\$\$` `<=` `(<=\$\$ x y z)` `>\$\$` `>` `(>\$\$ x y z)` `>=\$\$` `>=` `(>=\$\$ x y z)` `abs\$\$` `abs` `(abs\$\$ x)` `bounded-value\$\$` `bounded-value` `(bounded-value\$\$ x y z)` `ceiling\$\$` `ceiling` `(ceiling\$\$ x divisor)` `decf\$\$` `decf` `(decf\$\$ x delta)` `decf-\$\$after` `decf-after` `(decf\$\$-after x delta)` `decf/delete\$\$-acons` `decf/delete-acons` `(decf/delete\$\$-acons` `x delta alist)` `evenp\$\$` `evenp` `(evenp\$\$ x)` `fceiling\$\$` `fceiling` `(fceiling\$\$ x divisor)` `floor\$\$` `floor` `(floor\$\$ x divisor)` `ffloor\$\$` `ffloor` `(ffloor\$\$ x divisor)` `fround\$\$` `fround` `(fround\$\$ x divisor)` `ftruncate\$\$` `ftruncate` `(ftruncate\$\$ x divisor)` `incf\$\$` `incf` `(incf\$\$ x delta)` `incf\$\$-after` `incf-after` `(incf\$\$-after x delta)` `max\$\$` `max` `(max\$\$ x y z)` `min\$\$` `min` `(min\$\$ x y z)` `minusp\$\$` `minusp` `(minusp\$\$ x)` `mod\$\$` `mod` `(mod\$\$ x divisor)` `oddp\$\$` `oddp` `(oddp\$\$ x)` `plusp\$\$` `plusp` `(plusp\$\$ x)` `pushnew/incf\$\$-acons` `pushnew/incf-acons` `(pushnew/incf\$\$-acons` `'x delta alist)` `round\$\$` `round` `(round\$\$ x divisor)` `truncate\$\$` `truncate` `(truncate\$\$ x divisor)` `zerop\$\$` `zerop` `(zerop\$\$ x)`

The one-argument function coerce\$\$ provides convenient `double-float` coercion:

```  (setf x (coerce\$\$ x))
```

The GBBopen Project

 Double-float operators