New features
* Add UNDEF flag `undef_is_zero` in data section, https://github.com/equinor/fmu-dataio/pull/256
Bug fixes
* Check if number util function handles None, https://github.com/equinor/fmu-dataio/pull/257
* Fix issue when parameters.txt is missing, cf. 258, https://github.com/equinor/fmu-dataio/pull/259
**Full Changelog**: https://github.com/equinor/fmu-dataio/compare/1.1.1...1.1.2