**Changes**
- Implement variable substitutions on various levels; composite filter instances may override variables as needed
- fix https://github.com/ifm/nexxT/issues/53 (the C++ signature of signal propertyChanged() has changed)
- https://github.com/ifm/nexxT/issues/59 (--single-threaded, --disable-unload-heuristic, --no-profiling)
**Fixes**
- Fix overflow errors when loading recordings containing zero timestamps