Introduce alias for diary-float

* lisp/org-agenda.el (org-float): Aliases for `diary-float'.

This is just to make sure that all the diary sexp functions
have org- equivalents.  org-float is just an alias because no
arguments need to be switched around.

lisp/org-agenda.el

@@ -4841,6 +4841,7 @@ This function is invoked if `org-agenda-todo-ignore-deadlines',
   (org-no-warnings
    (let ((calendar-date-style 'european)	(european-calendar-style t))
      (diary-date day month year mark))))
+(defalias 'org-float 'diary-float)
 
 ;; Define the` org-class' function
 (defun org-class (y1 m1 d1 y2 m2 d2 dayname &rest skip-weeks)