Remove support for supertabular from RefTeX

* doc/misc/reftex.texi (Builtin Label Environments):
* lisp/textmodes/reftex-vars.el (reftex-label-alist-builtin)
(reftex-default-label-alist-entries): Delete entries for the
supertabular environment.  supertabular is an extension of the
normal tabular environment, and therefore doesn't contain a
caption and label.  Hence, supporting supertabular in RefTeX is
useless.

doc/misc/reftex.texi

@@ -1128,11 +1128,6 @@ the @code{\endnote} macro (from @file{endnotes.sty})
 the @code{\subfigure} and @code{\subtable} macros (from
 @file{subfig.sty})
 @item
-@cindex @code{supertab}, LaTeX package
-@cindex LaTeX packages, @code{supertab}
-@cindex @code{supertabular}, LaTeX environment
-@code{supertabular} (@file{supertab.sty})
-@item
 @cindex @code{wrapfig}, LaTeX package
 @cindex LaTeX packages, @code{wrapfig}
 @cindex @code{wrapfigure}, LaTeX environment

lisp/textmodes/reftex-vars.el

@@ -91,9 +91,6 @@
       ("\\subtable[][]{}"  ?t "tab:" "~\\subref{%s}"
        "\\\\subtable\\(?:\\(?:\\[[^]]*\\]\\)?\\[\\|{\\)")))
 
-    (supertab    "Supertabular environment"
-     (("supertabular" ?t nil nil "\\tablecaption{")))
-
     (wrapfig     "The wrapfigure and wraptable environments"
      (("wrapfigure" ?f nil nil caption)
       ("wraptable"  ?t nil nil caption)))
@@ -462,7 +459,7 @@ If nil, `follow-mode' will be suspended for stuff in unvisited files."
 
 (defcustom reftex-default-label-alist-entries
   '( amsmath endnotes fancybox floatfig longtable picinpar
-     rotating sidecap subfig supertab wrapfig
+     rotating sidecap subfig wrapfig
      listings minted ctable LaTeX)
   "Default label alist specifications.  LaTeX should always be the last entry.
 The value of this variable is a list of symbols with associations in the