Streamline external solver criteria
Moved version to 1.8.4, that includes the graphml output moved there from dose
Update the dependency to GitHub since the current source no longer exists.
The upstream site is currently down.
This should fix #563 Remark1: this will break the compilation of hosts which don't have md5 or md5sum installed. I'll add that in the sources. Remark2: I've writtent md5check in ML because md5 (on OSX) and md5sum (on linux) don't have the same command-line interface.
This is related to #387
This is not activated yet as need to wait for upstream changes and #387.