Fix massive position updates for OF_MOVEON_NOTIFY

In move.c (client) there was direct call to the BP_REQ_MOVE messagesender RequestMove(..).
But this sender does not care about updaterate/interval and this code runs fast and often sometimes.

So if the client moved on objects which were marked as OF_MOVEON_NOTIFY, like guildhall doors,
it created more than 8 position updates at once, probably much more (=flooding the server).

Instead of calling the messagesender directly, this calls the method which honors the intervals and only sends updates as required.

This bug was found by Gar when testing stuff with new speedhack protection.