EMI: Change frustum parameters for Overworld actors

- lower the distance to the near plane of the frustum for Overworld
  and change the other parameters accordingly

- this makes the following actors visible:
 - background of directions to Pegnose Pete's house (issue #869)
 - Murray in the murray_go easter egg
 - the trophies during the diving contest (upper left corner)
 - the screenshots for the save games (still with the wrong texture)