[tests.elliptic-gc-discretization] use vector interface
[cmake] use CMAKE_WITH_AUTOTOOLS=1 to enable the old behaviour
replace #ifdef with #if
[space...] remove unnecessary specialization
[space.interface] update
* use CRTPInterface from dune-stuff
* use stl naming for methods instead of camelCase
[space.interface]
[space.continuouslagrange] added base
[space.continuouslagrange.pdelab] derive from ContinuousLagrangeSpaceBase
[tests.spaces] update