Doc: add a section describing quickly the use of 'nor', '#', and n-ary xor

doc/lutin-man/language.tex

@@ -631,6 +631,30 @@ declare in  the combinator profile that  it is a  reference using the
 Another  example  of the  use  of  reference  variables is  given  in
 Section~\ref{up-and-down}.
 
+\subsubsection{Pre-defined combinators: nor, xor, and \#}
+\label{Pre-defined-combinators}
+
+Some useful combinators are predefined to state that, among a list of
+Boolean expressions:
+
+\begin{itemize}
+\item none is true (\key{not})
+\item exactly one is true (\key{xor})
+\item exactly zero or one is true (\key{\#})
+\end{itemize}
+
+
+\begin{example}
+  \begin{program}
+    \key{node} N() \key{returns} (\key{x,y,t}:bool) = \\
+        \{ \\
+          | \key{nor}(x,y,z) or \key{xor}(x,y,z) \\
+          | \#(x,y,t) -- actually equivalent to the previous line\\
+        \}
+\end{program}
+\end{example}
+
+
 
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 \subsection{Calling external code}

doc/lutin-man/tokens

@@ -57,7 +57,10 @@ TK_OPEN_PAR          (
 TK_CLOSE_PAR         )
 TK_NOT         not
 TK_OR          or
+TK_NOR         nor
 TK_XOR         xor
+TK_NXOR        xor
+TK_DIESE       #
 TK_AND         and
 TK_IMPL        =>
 TK_ARROW       ->

lutin/src/lutParser.mly

@@ -875,7 +875,7 @@ lutBinExp:
 	|	lutExp TK_LTE lutExp { make_val_exp (CALL_n (flagit "lte" $2, [$1;$3])) $2 }
 	|	lutExp TK_GT lutExp { make_val_exp (CALL_n (flagit "gt" $2, [$1;$3])) $2 }
 	|	lutExp TK_GTE lutExp { make_val_exp (CALL_n (flagit "gte" $2, [$1;$3])) $2 }
-   
+   ;
 lutNaryExp:
    /* n-ary */
    |  TK_DIESE TK_OPEN_PAR lutExpList TK_CLOSE_PAR
@@ -884,7 +884,7 @@ lutNaryExp:
         { make_val_exp (CALL_n (flagit "nor" $1, (List.rev $3))) $1 }
    |  TK_XOR TK_OPEN_PAR lutExpList TK_CLOSE_PAR
         { make_val_exp (CALL_n (flagit "nxor" $1, (List.rev $3))) $1 }
-        
+   ;    
 lutExpList:   
 		/* empty */
         { [] }