Built libraries have unversioned SONAMEs

[morxa]

All libraries have no version in the SONAME:

/usr/lib64/libopcuaclient.so	libopcuaclient.so
/usr/lib64/libopcuacore.so	libopcuacore.so
/usr/lib64/libopcuaprotocol.so	libopcuaprotocol.so
/usr/lib64/libopcuaserver.so	libopcuaserver.so

This makes it difficult to detect the compatibility of different versions of the library. This also blocks me from submitting freeopcua to the Fedora repositories, which I'm currently working on.

This is closely related to #294. Note that library version and SONAME version do not necessarily need to be the same, i.e., you can provide SONAMEs without specifying library version (and vice versa).