[core] change calling syntax for defaults decorator
[parameters] add random_state argument to CubicParameterSpace.sample_randomly
[core] bugfix in defaults implementation
[test] update test for defaults
[core] include _default_container.sid in sid generation
[core] improve documentation
[core] use defaults_sid() instead of _default_container.sid
[core.defaults] add defaults_sid method
[core.cache] use defaults_sid()
[operators] ensure that defaults have not changed in caching for assemble
[la] ensure that sparse_options for numpy solvers are recomputed if defaults change
[core.defaults] allow changing defaults even if sids have been calculated
[core.defaults] improve some parameter names
[core.defaults] improve behaviour of set_defaults