update todo list

TODO.md

@@ -9,9 +9,23 @@
   1. single pass (fast) load
   2. micro-patches / bare bones observation API / fully hydrated documents
 
+### future:
+  1. handle columns with unknown data in and out
+  2. branches with different indexes
+
+### Peritext
+  1. add mark / remove mark -- type, start/end elemid (inclusive,exclusive)
+  2. track any formatting ops that start or end on a character
+  3. ops right before the character, ops right after that character
+  4. query a single charaacter - character, plus marks that start or end on that character 
+     what is its current formatting,
+     what are the ops that include that in their span,
+     None = same as last time, Set( bold, italic ),
+     keep these on index
+  5. op probably belongs with the start character - possible packed at the beginer or end of the list
+
 ### maybe:
   1. tables
 
 ### no:
   1. cursors
-