Elevatorsion

1. Bug fixes:
   1. Fix a bug makes able to call elevator at 2 different floor
   2. Now elevator's can move after server crashes when the elevator move.
2. Add:
   1. A message for all player in the elevator like "Going up..." in chat.

Certain blocks can makes some problem, for exemple wood button not supported.
Some development warning message in server console can be appear.