Headers files are installed into `<prefix>/include/include`

[roxlu]

The include files are installed into <prefix>/include/include. This should probably be something like <prefix>/include/skribidi which can be fixed by changing this:

	install(
		DIRECTORY "${CMAKE_CURRENT_SOURCE_DIR}/include"
		DESTINATION ${CMAKE_INSTALL_INCLUDEDIR}
	)

Into:

	install(
		DIRECTORY "${CMAKE_CURRENT_SOURCE_DIR}/include/"
		DESTINATION ${CMAKE_INSTALL_INCLUDEDIR}/skribidi
	)

[memononen]

That makes sense, can you make a PR?