(undo_limit, undo_strong_limit, Vundo_outer_limit): Quadruple undo

limits (bug#1501).

src/undo.c

@@ -689,7 +689,7 @@ value, the earlier commands that came before it are forgotten.
 
 The size is counted as the number of bytes occupied,
 which includes both saved text and other data.  */);
-  undo_limit = 20000;
+  undo_limit = 80000;
 
   DEFVAR_INT ("undo-strong-limit", &undo_strong_limit,
 	      doc: /* Don't keep more than this much size of undo information.
@@ -701,7 +701,7 @@ is never discarded for this reason.
 
 The size is counted as the number of bytes occupied,
 which includes both saved text and other data.  */);
-  undo_strong_limit = 30000;
+  undo_strong_limit = 120000;
 
   DEFVAR_LISP ("undo-outer-limit", &Vundo_outer_limit,
 	      doc: /* Outer limit on size of undo information for one command.
@@ -718,7 +718,7 @@ In fact, this calls the function which is the value of
 `undo-outer-limit-function' with one argument, the size.
 The text above describes the behavior of the function
 that variable usually specifies.  */);
-  Vundo_outer_limit = make_number (3000000);
+  Vundo_outer_limit = make_number (12000000);
 
   DEFVAR_LISP ("undo-outer-limit-function", &Vundo_outer_limit_function,
 	       doc: /* Function to call when an undo list exceeds `undo-outer-limit'.