[basefunctionset.pdelab] fixed jacobian()
[basefunctionset.pdelab] update
* replaced override -> final in virtual functions
* specialize for range 1x1 and give a static error otherwise
* some notes and clean up
[mapper.pdelab]
[space.continuouslagrange.pdelab]
* updated use of BaseFunctionSet
* implemented localConstraints
[operator.projections] added pdelab combination
[test.spaces] major update
* added a test for P1Q1 continuous lagrange spaces
* restructured a lot
[tests.elliptic...discretization] assemble only once
[tests.elliptic-swipdg-discretization]