* add support for systemd, OpenRC, SysVinit, and Dinit
* add automatic init-system detection through CMake
* make libsystemd optional for non-systemd builds
* add native service definitions for all supported init systems
* add Gentoo ebuild and Alpine APKBUILD packaging support
* publish the official BastionGuard source repository
* update the README with supported distributions, init systems, repository information, and build documentation
