change line indexing in AppUpdate.moveToLine from 0-based to 1-based (so first line can be access with 1G, second with 2G, as is normal with Vim)

fcore/app-update.sml

@@ -69,8 +69,13 @@ struct
       val bufferLine = bufferLine - 1
 
       val buffer = LineGap.goToIdx (bufferIdx, buffer)
-      val bufferLine = TextWindow.getStartLineWithCursorCentered 
+      val bufferLine = 
-        (buffer, bufferIdx, bufferLine, windowWidth, windowHeight)
+        let
+          val maxHeight = windowHeight - (TextConstants.ySpace * 2)
+        in
+          TextWindow.getStartLineWithCursorCentered 
+            (buffer, bufferIdx, bufferLine, windowWidth, maxHeight)
+        end
 
       val buffer = LineGap.goToLine (bufferLine, buffer)
       val drawMsg = 
@@ -85,6 +90,9 @@ struct
     end
 
   fun moveToLine (app: app_type, reqLine) =
+    if reqLine = 0 then
+      moveToStart app
+    else
       let
         val {windowWidth, windowHeight, buffer, startLine = origLine, ...} = app
         val buffer = LineGap.goToLine (reqLine, buffer)
@@ -285,7 +293,7 @@ struct
          if String.size str = 0 then
            moveToEnd app
          else
-           moveToLine (app, count)
+           moveToLine (app, count - 1)
     | #"%" => moveToMatchingPair app
     (* multi-char commands which can be appended *)
     | #"t" => appendChr (app, chr, str)