Enrage PI alert animal sounds

The following short PI alert sounds were made from freely licensed Wikimedia Commons audio files:

- pi-cat-meow.ogg: based on "Meow.ogg" by Dcrosby, licensed CC BY-SA 3.0.
  Source: https://commons.wikimedia.org/wiki/File:Meow.ogg
  License: https://creativecommons.org/licenses/by-sa/3.0/

- pi-dog-bark.ogg: based on "Barking of a dog.ogg" by Amada44, licensed CC BY-SA 3.0.
  Source: https://commons.wikimedia.org/wiki/File:Barking_of_a_dog.ogg
  License: https://creativecommons.org/licenses/by-sa/3.0/

- pi-cat-plead.ogg: based on "Meow of a pleading cat.oga" by Heismark, public domain.
  Source: https://commons.wikimedia.org/wiki/File:Meow_of_a_pleading_cat.oga

- pi-prairie-bark.ogg: based on "Cynomys ludovicianus barking-audio.ogg" by W0lfie, public domain.
  Source: https://commons.wikimedia.org/wiki/File:Cynomys_ludovicianus_barking-audio.ogg

- pi-rooster.ogg: based on "Medium rooster crowing.ogg" by alys / PDSounds, public domain.
  Source: https://commons.wikimedia.org/wiki/File:Medium_rooster_crowing.ogg

- pi-goat.ogg: based on "Herd of goats bleating.ogg" by stephan / PDSounds, public domain.
  Source: https://commons.wikimedia.org/wiki/File:Herd_of_goats_bleating.ogg

- pi-duck.ogg: based on "Ducks landing in water.ogg" by U.S. Fish and Wildlife Service, public domain.
  Source: https://commons.wikimedia.org/wiki/File:Ducks_landing_in_water.ogg

- pi-moo.ogg: based on "En-us-moo.ogg" by Mx. Granger, CC0 1.0.
  Source: https://commons.wikimedia.org/wiki/File:En-us-moo.ogg
  License: https://creativecommons.org/publicdomain/zero/1.0/

Files were shortened and normalized for use as in-game alert sounds.
