v0.68.0

What's Changed

• Fix non-conformant use of iterator type aliases by @stephenswat in #755
• Migrate static strings to std::string_view by @stephenswat in #756
• Add a test for helix radius by @beomki-yeo in #758
• fix: suggest parentheses around comparison in operand of '|' warning by @fredevb in #757
• ref: Make Newton convergence more robust by @niermann999 in #754
• ref: Update to new actsvg version and fix some bugs by @niermann999 in #759
• ref: add momentum information to file names and finalize plots by @niermann999 in #760
• ref: Rename volume and surface classes by @niermann999 in #761
• ref: Use relative error in material comparison and improve material plots by @niermann999 in #762

Full Changelog: v0.67.0...v0.68.0