* Improve devendoring
* Add warning flags for own C++ code
For https://github.com/tildearrow/furnace/pull/12#issuecomment-1017330467.
* Document new CMake options
* pkg-config stuff
* Warnings stuff for MSVC yay
* Use more specific linking vars & functions
* Fix Linux icon location
* DEPENDENCIES_LEGACY_LDFLAGS for JACK too