Merve dont_move_cursor and hold_refresh into a single hold_update.

Should be set to true when many updates are being done and they don't need
to be shown as they happen.  After setting back to 0, any ciolib function
should do the full update.

Win32: The cursor doesn't move while hold_update is set.
Curses: No refresh() is called while hold_update is set.

This allows programs to be faster without compromising conio compatability.