- removed some redundant version numbers for certain GNU tools required

   from manual texi


Docs/manual.texi:
   - removed version numbers of GNU tools from the feature list
     (they are going to change from time to time again and the current
     required version number should probably be kept in one chapter only)

Docs/manual.texi

@@ -548,8 +548,7 @@ Written in C and C++.  Tested with a broad range of different compilers.
 @item
 Works on many different platforms.  @xref{Which OS}.
 @item
-Uses GNU Automake (1.4), Autoconf (Version 2.52 or newer), and Libtool for
-portability.
+Uses GNU Automake, Autoconf, and Libtool for portability.
 @item
 APIs for C, C++, Eiffel, Java, Perl, PHP, Python, Ruby, and Tcl.
 @xref{Clients}.