Broken library links / sources.conf links

Issue description

These links from the processing.org libraries page

https://processing.org/reference/libraries/

are broken / 404, and need to be updated or removed:

• Andres Colubri -- home domain is gone
  • Eliza http://interfaze.info/libraries/eliza/
  • Tablet http://interfaze.info/libraries/tablet/
• AULib https://imaginary-institute.com/resources/AULibrary/AULib.php
  • URL now uses the full word "Library" https://imaginary-institute.com/resources/AULibrary/AULibrary.php
• GML4U https://github.com/01010101/GML4U/wiki
  • should possibly point to: http://www.graffitimarkuplanguage.com/gml4u/ https://github.com/joshuajnoble/GML4U
• NextText http://nexttext.net/
  • possibly should be https://github.com/prisonerjohn/NextText
• SFT https://shiffman.net/2007/06/04/sftp-with-java-processing/
  • It looks like SFTP info should be updated here: https://shiffman.net/p5/libraries/sftp/sftp.txt
  • and point to https://shiffman.net/java/library/p5/processing.org/programming/sftp/2007/06/04/sftp-with-java-processing/
• Steganos http://www.lagers.org.uk/steganography
  • updated link: http://www.lagers.org.uk/steganos/index.html