Fix CopyLine at the last empty line of buffer

When the cursor is at the last line of buffer and it is an empty line,
CopyLine does not copy this line, which is correct, but it shows a bogus
"Copied line" message. Fix this by adding a check for that, same as in
CutLine and DeleteLine.

internal/action/actions.go

@@ -1181,6 +1181,9 @@ func (h *BufPane) CopyLine() bool {
 	origLoc := h.Cursor.Loc
 	origLastVisualX := h.Cursor.LastVisualX
 	h.Cursor.SelectLine()
+	if !h.Cursor.HasSelection() {
+		return false
+	}
 	h.Cursor.CopySelection(clipboard.ClipboardReg)
 	h.freshClip = true
 	InfoBar.Message("Copied line")