Enigma Source (svn, archived)

- speedup of World::handle_contacts() by factor of appr. 4
- eliminate usage of slow StoneContactList
- rewrite find_stone_contacts() with min. detail examinations
- find_contact_with_stone() eliminate expensive dist calc
- fix bug in find_contact_with_stone() that allowed a horse to penetrate
stones at the rounded edges by 4.72 pixels
- outcommented unused actor oldpos ivar
- perfomance of engine part did increase about factor 4 since 1.0