I accidentally broke c++ ABI compatibility between 2.1.0 and 2.2.0. This is fixed here. This release is only of relevance for package maintainers caring about ABI stability of MINOR version changes according to semantic versioning. None of the wrappers are effected by this change and hence will not be released as 2.2.1.
DISCLAMER: Unfortunately, it turned out that the above mentioned fix for the c++ ABI can break your build if you have some kind of globally enabled pre-compiled-header setup, like apparently in libreoffice (see #685). In that case, either disable pre-compiled-headers or use 2.2.0.
Full Changelog: v2.2.0...v2.2.1