(svn r2595) -Codechange: Introduced "IsSteepTileh" to find whether a tile is steep
(i.e. spans two height levels) and use it throughout the code.
-Codechange: Add CanBuildDepotByTileh to find if a tile is suitable to
build a depot on it. Wraps some bitmagic which seems quite unreadable at
first glance

#ifndef CALLBACK_TABLE_H
#define CALLBACK_TABLE_H

extern CommandCallback *_callback_table[];
extern const int _callback_table_count;

#endif