Release v6.6.0: improved cross-section models

Following the introduction transient cross-section models in TTim , this new version introduces a dedicated cross-section Model class, some more user-friendly element naming and other minor improvements.

What's Changed

• Refactor StripInhoms by @dbrakenhoff in #121
• Release 6.6.0: refactor cross-sections by @dbrakenhoff in #122

Full Changelog: v6.5.0...v6.6.0