update submodules, determine number of CPU cores.
remove obsolete unity build

I used to speed up compilation by reducing the number of compilation
units with this hack. It's no longer done this way, so let me kill the
supporting files here.
Do not try to load a default lua file.

The default behavior is now that the game goes to the console without
loading setup.lua, unless setup.lua is specified in eressea.ini as the
script to be run.
Should add an option to override this from the command line, too.
I am killing the core/ directory.
Lots of files are moving to a new location in src/
Some intersting CMake changes.
Merge branch 'master' of github.com:eressea/server
add lua integration tests to `make test`.
added message about missing source files. Maybe should be an error and not a warning.