title: how to integrate .net library (.dll) from higher version with binaries from lower version
body: <p>I have external .net library compiled with .net framework 4 (it's provider moved recently to .net 4)
  My code currently runs on .net framework 3.5
  How to use that external library in my application ?
  Moving whole application to .net 4 needs time and testing, so maybe in a future i will do that, but now, what are the possibilities ?</p>