Update a few runtime files.

runtime/doc/todo.txt

@@ -1,4 +1,4 @@
-*todo.txt*      For Vim version 8.2.  Last change: 2019 Dec 24
+*todo.txt*      For Vim version 8.2.  Last change: 2020 Jan 02
 
 
 		  VIM REFERENCE MANUAL	  by Bram Moolenaar
@@ -38,6 +38,8 @@ browser use: https://github.com/vim/vim/issues/1234
 							*known-bugs*
 -------------------- Known bugs and current work -----------------------
 
+- Implement prop_find() issue #4970  Done by Ryan Hackett, #5421
+
 Include ipv6 syntax changes?  (DJ Lucas, #5360)
 
 Still have /* */ comments:
@@ -50,7 +52,9 @@ Popup windows:
   input?  Sort-of possible by creating a hidden terminal and opening a popup
   with that buffer: #4063.
 - Use popup (or popup menu) for command line completion
-- Implement flip option
+- When using a popup for the info of a completion menu, and there is not
+  enough space, let the popup overlap with the menu. (#4544)
+- Implement flip option.
 - Make redrawing more efficient and avoid flicker:
     - put popup menu also in popup_mask?
 - Any other commands to disable in a popup window?
@@ -58,7 +62,6 @@ Popup windows:
 - Figure out the size and position better if wrapping inserts indent
 
 Text properties:
-- Implement prop_find() issue #4970
 - Text properties spanning more than one line
 - See remarks at top of src/textprop.c
 
@@ -125,7 +128,7 @@ Terminal emulator window:
   conversions.
 
 Error numbers available:
-E292, E362, E366, E450, E451, E452,
+E362, E366, E450, E451, E452,
 E453, E454, E460, E489, E491, E565, E578, E610, E611, E653,
 E654, E856, E857, E860, E861, E863, E889, E900
 
@@ -192,6 +195,8 @@ It can replace the BeOS code, which is likely not used anymore.
 Now on github: #1856.  Updated Oct 2017
 Got permission to include this under the Vim license.
 
+Add "t" action to settagstack(): truncate and add new entries. (#5405)
+
 Result of synID() sometimes wrong in help files. (#5252)
 
 Problem showing a line if the number column width changes when using "o".