tng_io-configVersion.cmake: has no version
When building tng standalone tng_io-configVersion.cmake has no version in it:
$ head -1 cmake/tng_io-configVersion.cmake set(PACKAGE_VERSION "")
The problem is due to the fact that TNG_IO_VERSION gets set in TNG_GENERATE_VERSION_H(), but not globally. And parent_scope TNG_GENERATE_VERSION_H() makes it only visible in add_tng_io_library(), but not globally.
There are main ways to fix this, one would to set version globally with
project(TNG_IO VERSION 1.8.0)