walk correction notice

Created by: Helianthella

this is a fix for the following bug:

1. die or sit
2. @jump (or warp or goto or anything that changes your map)
3. you will be standing... press any arrow key and you re-die

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For the correction notice, see https://github.com/ManaPlus/ManaPlus/blob/master/src/net/tmwa/playerhandler.cpp#L367