Doomsday Engine

Improvements in the Heretic plugin:
* Intermission shows map play time
* Intermission doesn't show "Untitled" as the next map
* Added "take" cheat command (opposite of "give")
* Player sound effects as a chicken (e.g., laugh)
* Non-bleeders shouldn't bleed when crushed

The following modding features are implemented in the Heretic plugin:
* Added "Intermission background" to the Map Info DED definition (defaults to "Flats:FLOOR16")
* Values for overriding intermission text labels: "Intermission Label|{text}", e.g., "Intermission Label|Finished"
* The values "Menu Label|Episode Page Title" and "Menu Label|Skill Page Title" can be set to override the corresponding menu titles
* Defining ammo per shot with Values
* DED Map Info flag @mif_dim_torch@: use the Hexen torch rendering mode with light attenuation
* MF3_WALLBOUNCE causes a missile to bounce off walls (adapted from Hexen)
* MF_DROPOFF causes objects to fall gently, with gravity, instead of teleporting to floor height
* Added World.Thing.attack() script method World.Thing.attack() for executing a thing's attack

In addition, the following is also implemented:
* Value definitions can be used to replace menu text labels and page titles (e.g., the value definition "Menu Label|{old-label}" is used instead of "{old-label}" in menus
* Placing the comment @// Doomsday: Ignore errors!@ in a MAPINFO lump will cause Doomsday to silently ignore any unsupported features in the lump.
* Added script method: World.Thing.recoil()