Install/uninstall scripts

[glixx]

Needs to have script, what will install files into target dir.
./do install prefix, where prefix is parameter or / (root) by default.

So %install section of spec file will be:
./do install %{buildroot}

It needs not only for packaging, but for installation directly in system without package. If gcad3d was installed directly, then needs to have uninstall script.