reimplement 't' movement motion the same way that 'f' movement motion was reimplemented in previous commit

fcore/normal-mode/normal-mode.sml

@@ -565,7 +565,7 @@ struct
          * tillNextChr with count of 1 has same effect
          * as tillNextChr with any count above 1
          * so just hardcode 1 *)
-        parseMoveToChr (1, app, Cursor.tillNextChr, chrCmd)
+        NormalMove.tillNextChr (app, count, chrCmd)
     | #"T" =>
         (* to just before chr, backward *)
         parseMoveToChr (1, app, Cursor.tillPrevChr, chrCmd)

fcore/normal-mode/normal-move.sml

@@ -530,4 +530,18 @@ struct
         NormalFinish.buildTextAndClear
           (app, buffer, newCursorIdx, searchList, [], bufferModifyTime)
     end
+
+  fun tillNextChr (app: app_type, count, chr) =
+    let
+      val {cursorIdx, buffer, searchList, bufferModifyTime, ...} = app
+      val buffer = LineGap.goToIdx (cursorIdx, buffer)
+      val newCursorIdx =
+        Cursor.toNextChrNew (buffer, cursorIdx, {findChr = chr, count = count})
+    in
+      if newCursorIdx = ~1 then
+        NormalFinish.clearMode app
+      else
+        NormalFinish.buildTextAndClear
+          (app, buffer, newCursorIdx - 1, searchList, [], bufferModifyTime)
+    end
 end