moved space -> spaces
[spaces] major renaming
* ContinuousLagrangeSpaceBase -> Spaces::ContinuousLagrangeBase
* ContinuousLagrangeSpace::FemWrapper
  -> Spaces::ContinuousLagrange::FemBased
* ContinuousLagrangeSpace::FemLocalfunctionsWrapper
  -> Spaces::ContinuousLagrange::FemLocalfunctionsBased
* ContinuousLagrangeSpace::PdelabWrapper
  -> Spaces::ContinuousLagrange::PdelabBased
* DiscontinuousLagrangeSpace::FemLocalfunctionsWrapper
  -> Spaces::DiscontinuousLagrange::FemLocalfunctionsBased
* RaviartThomasSpace::FemLocalfunctionsWrapper
  -> Spaces::RaviartThomas::FemLocalfunctionsBased
* FiniteVolumeSpace::Default
  -> Spaces::FiniteVolume::Default