0.9.4

This CRAN release focuses on stability, documentation, and preparing the
ground for a forthcoming major release:

• Dependencies: Updated for modern dplyr and tidyr, removed use
  of deprecated mutate_if() and plyr::mapvalues().
• Bug fixes:
  • Restored reproducibility of the germany_1995 dataset from the
    Eurostat Manual (Beutel, 2008).
  • Corrected documentation mismatches for datasets and test results.
  • Improved spelling consistency (en-GB).
• Documentation:
  • Expanded vignette on terminology (work in progress) to align
    future terminology with Eurostat, UN, and OECD manuals.
  • Clarified dataset origins (netherlands_2000, uk_test_results,
    germany_airpol) and improved examples/tests against published
    results.
  • Improved developer notes in data-raw/ to ensure reproducibility of
    bundled datasets.
  • Improved and modernised testthat suite for better unit testing and
    153 new unit tests.
  • Website: cleaned configuration, fixed missing URL and
    reference errors.

This version maintains backward compatibility with previous 0.9.3 (CRAN)
releases, while setting the stage for a future 1.0 release with
extended SIOT sources, enhanced reliability, and new functionality.

What's Changed

• Devel by @antaldaniel in #31
• Devel by @antaldaniel in #40
• documentation and test improvements by @antaldaniel in #41

Full Changelog: 0.9.3...0.9.4