Release candidate 2 of version 4.3

Please test and report issues.
This pre-release is based on the to4.3 branch:
https://github.com/dalesteam/dales/tree/to4.3
General DALES 4.3 change log: https://github.com/dalesteam/dales/blob/to4.3/CHANGELOG.md
Compared to release candidate 1, mainly multiple bug fixes and optimizations that do not affect results have been added.