I have a program called Unity Assets Explorer by Haoose,it can extract some stuff from unity files ,i'm sure there is other progs. out there too.
I think it's on v1.5 not sure . Read this(SCROLL DOWN THE PAGE) : http://www.alanzucconi.com/2015/09/02/a-practical-...
ALSO:
Unity Studio is a tool for exploring, extracting and exporting assets from Unity games and apps. http://forum.xentax.com/viewtopic.php?f=10&t=11807
also maybe read this , http://rimworldwiki.com/wiki/Modding_Tutorials/Ass...