Wrong version of Eigen3

[mattagape]

File cmake_files/dependencies.cmake attempts to download Eigen 3.2. But the MD5 hash in the file is wrong.

I can't see where the "official" hash versions are on the Eigen website so have no way of knowing if the new hash value is OK or not. (A .tar.gz hash value will change if the gzip was done again, at a later time)

Also, the README file says that Eigen v3.3.7 (Trusty) is required.

[mattagape]

NB SOPT appears to be using Eigen 3.2