Fix in the hack index -> character; all of those things need to be revisited for robustness and performance!

4ed_buffer.cpp

@@ -1016,6 +1016,13 @@ buffer_layout_character_from_pos(Buffer_Layout_Item_List list, i64 index){
     i64 result = 0;
     i64 character_count = 0;
     i64 prev_index = -1;
+    if (index <= list.index_range.first){
+        result = 0;
+    }
+    else if (index > list.index_range.one_past_last){
+        result = list.character_count - 1;
+    }
+    else{
         for (Buffer_Layout_Item_Block *node = list.first;
              node != 0;
              node = node->next){
@@ -1032,6 +1039,7 @@ buffer_layout_character_from_pos(Buffer_Layout_Item_List list, i64 index){
                 }
             }
         }
+    }
     double_break:;
     return(result);
 }