Encumbrance messagebox timer works incorrectly

Steps to reproduce:

1. Take more items than player character can carry.
2. Press and release move button. A sNotifyMessage59 Messagebox appears.
3. Press and release move button again. Messagebox does not appear.

It is because mOverencumberedMessageDelay timer (one second between message boxes) ticks only if player tried to move in given frame. In original engine timer ticks even if player did not move in this frame.

Also if you hold move button, OpenMW spawns a new sNotifyMessage59 messagebox every second, while original engine just increases a lifetime of previous one, if it is present. Not sure if it is worth to replicate, though.