Eigen website down #989
Description
Not an issue with ORB-SLAM3, but an issue with a prerequisite.
The website hosting the download and install instructions for Eigen3, http://eigen.tuxfamily.org/, is down, at least currently. The code is available at https://gitlab.com/libeigen/eigen/-/tree/3.4?ref_type=heads, and the install instruction are available in the INSTALL file. Might be worth updating the Prerequisites with the gitlab site instead if the Eigen website continues being unreachable.