Johannes Lorenz

@PhysSong Concerning the CI, I'd rather not use `ExternalProject_Add`, since it means building LMMS twice (and building zyn and mruby zest unnecessarily). I'd suggest to compile all CI tests with...

> Can you elaborate it? I meant building SPA using it. Oh, I think I got you completely wrong. That sounds reasonable, I'll try it out.

Things to be done: * check memory cleanup. `std::unique_ptr` should be used instead of pointers, and `make_unique` should be used to initialize them. * check for usage of new style...

As this whole branch is currently not meant to be merged, I convert it to "draft".

I just pushed a new v0.2.2 to [lmms-zyn-fusion-test repo](https://github.com/JohannesLorenz/lmms-zyn-fusion-test/issues). It contains most up-to-date version of LMMS (current master + osc-host), zyn (current master + osc-plugin), the "zyn-fusion" UI and SPA....

> Do the advantages / disadvantages in the PR description still apply or has the situation changed since 2018? After all, it's been almost 4 years, and some software changes...

I think the additional dependency is not a problem if we can set it as optional in CMake and then use `#ifdef`s to use or not use it?

As the build shows, your PR fails the CI on all machines: ``` CMake Error at /usr/share/cmake-3.10/Modules/FindPackageHandleStandardArgs.cmake:211 (message): No REQUIRED_VARS specified for FIND_PACKAGE_HANDLE_STANDARD_ARGS() Call Stack (most recent call first): cmake/modules/FindFFmpeg.cmake:97...

### In general: I am in favor for removing Qt from the core, especially because many Qt things are [not realtime-safe](https://github.com/LMMS/lmms/wiki/Realtime-conventions#qt-data-structures), so it's a good preparation. E.g., due to the...

I don't worry much that this would be another reorg, because I wouldn't expect too many merge conflicts with existing PRs (but maybe I'm wrong). E.g. there are not that...