update TODO with a bunch of select tasks

TODO.md

@@ -19,17 +19,19 @@ Correctness:
 * test wrap against wraptest: https://github.com/mattiase/wraptest
   - automate this in some way
 
-Visual:
-
-* bell
-
 Improvements:
 
 * scrollback: configurable
+* selection on top/bottom should scroll up/down (while extending selection)
+* double-click to select a word
+* triple-click to select a line
+* shift-click and drag to continue selection
+* arrow keys do nothing, should send proper codes
+* home/end should scroll to top/bottom of scrollback
 
 Major Features:
 
 * Strikethrough
 * Emoji
 * Ligatures
-
+* Bell