* replace Git tarball by upstream release tarball
* use proper SONAME (libxpp-0_2_0 wasn't the SONAME, now it is libxpp-3)
* minor changes in the code:
- consistently marm move ctors and operators as noexcept
- improvements in the build system
- use new libcosmos dependency
OBS-URL: https://build.opensuse.org/package/show/X11:XOrg/libxpp?expand=0&rev=14
