Updated Travis-CI to use Ubuntu 18.04 worker with versions of libMesh >= 1.4.1 and for the documentation/website builds. Builds using the older Ubuntu 16.04 worker are still used for libMesh version 1.3.1 since I could not get libMesh to build using standard Ubuntu 18.04 package repositories without a lot of work.
In all the current releases of libMesh (including 1.5.1) there are some conflicts that occur with the metis library that is built alongside libMesh and the one that is provided by Ubuntu 18.04 repositories. After v1.5.1 the libMesh developers added an option use and external metis to the libMesh configure. I successfully back-ported this to the v1.5.1 and v1.4.1 releases without too much trouble. It wouldn't work on v1.3.1 release without more effort.
I could make the upgrade to Ubuntu 18.04 on the older versions of libMesh by building more of the dependencies manually and not using apt provided packages, but that is more work than I want to do right now.
The main reason to upgrade to Ubuntu 18.04 is that it provides a newer version of doxygen that has some improved features like picture resizing. Ubuntu 16.04 also goes end-of-life in April 2021 so I suspect Travis-Ci will stop supporting it at some point.
Updated Travis-CI to use Ubuntu 18.04 worker with versions of libMesh >= 1.4.1 and for the documentation/website builds. Builds using the older Ubuntu 16.04 worker are still used for libMesh version 1.3.1 since I could not get libMesh to build using standard Ubuntu 18.04 package repositories without a lot of work.
In all the current releases of libMesh (including 1.5.1) there are some conflicts that occur with the metis library that is built alongside libMesh and the one that is provided by Ubuntu 18.04 repositories. After v1.5.1 the libMesh developers added an option use and external metis to the libMesh configure. I successfully back-ported this to the v1.5.1 and v1.4.1 releases without too much trouble. It wouldn't work on v1.3.1 release without more effort.
I could make the upgrade to Ubuntu 18.04 on the older versions of libMesh by building more of the dependencies manually and not using apt provided packages, but that is more work than I want to do right now.
The main reason to upgrade to Ubuntu 18.04 is that it provides a newer version of doxygen that has some improved features like picture resizing. Ubuntu 16.04 also goes end-of-life in April 2021 so I suspect Travis-Ci will stop supporting it at some point.