Add Installation for Dependency without Submodules

[SSoelvsten]

Some user's would like to build Adiar once and then install it. This way, you do not need to include it as a submodule to each of your projects (and build it for each of them independently).

Note: This should then also be made to work with CMake's find_package.

Note: People may depend on multiple versions of Adiar. Hence, one should install it with the version number suffixed. Look here for how to do so.