## Summary of Changes
Turn several copies into `const&` to avoid allocation of data members of
traits object with multiprecision coordinates. In release mode the gain
is around 10%..
To address the timeouts in the testsuite in Debug mode, I also changed
cell size and approximation error.
## Release Management
* Affected package(s): Periodic_triangulation_3_mesh_3
* License and copyright ownership: unchanged
Sebastien Loriot
166681a6ce