dune-ax1: Public release 1.0

This is the first public release of the Dune module dune-ax1. It is based on the current master branches of PDELab and the other Dune modules it depends on. Please refer to the README.md file for detailed information.

Please note that this release will not be updated according to changes in the other Dune modules' master branches. In order to get this module up and running, you will need to use specific revisions from the other modules. Please refer to the file INSTALL.md for instructions.

Alternatively, you can use one of the maintenance branches based on PDELab 1.1 or 2.0 releases, respectively. However, these branches do not contain the functionality added on the master branches since their creation.