"singed" --> "signed" (3 places)

Noticed by Andrew MacIntyre <andymac@bullseye.apana.org.au>.

Doc/lib/libfuncs.tex

@@ -230,7 +230,7 @@ removed.
 
 \begin{funcdesc}{float}{x}
   Convert a string or a number to floating point.  If the argument is a
-  string, it must contain a possibly singed decimal or floating point
+  string, it must contain a possibly signed decimal or floating point
   number, possibly embedded in whitespace;
   this behaves identical to \code{string.atof(\var{x})}.
   Otherwise, the argument may be a plain or
@@ -305,7 +305,7 @@ module from which it is called).
 
 \begin{funcdesc}{int}{x}
   Convert a string or number to a plain integer.  If the argument is a
-  string, it must contain a possibly singed decimal number
+  string, it must contain a possibly signed decimal number
   representable as a Python integer, possibly embedded in whitespace;
   this behaves identical to \code{string.atoi(\var{x})}.
   Otherwise, the argument may be a plain or
@@ -355,7 +355,7 @@ the interpreter.
 
 \begin{funcdesc}{long}{x}
   Convert a string or number to a long integer.  If the argument is a
-  string, it must contain a possibly singed decimal number of
+  string, it must contain a possibly signed decimal number of
   arbitrary size, possibly embedded in whitespace;
   this behaves identical to \code{string.atol(\var{x})}.
   Otherwise, the argument may be a plain or