[function] removed, was deprecated long enough :)
[functions.interfaces] introduced new Interfaced

LocalfunctionSetInterface, LocalfunctionInterface and
LocalizableFunctionInterface. Also marked FunctionInterface
as deprecated and removed matrix valued one
[functions.constant] updated to new interface

matrixvalued implementation is still missing
[functions.interfaces] added missing const
[functions.interfaces] readded fem includes
[functions.visualization] added Function::VisualizationAdapter
[functions.interfaces] specialized LocalizableFunctionInterface

for scalar and vector valued functions
[functions.interfaces] added visualize()
[functions.constant] added missing const
[la.container.eigen] removed createIdentityEigenRowMajorSparseMatrix
[la.container.eigen] added c++11 move semantics

to all but the double* map, since I have now idea
what the memory management looks like for that one
[function.interfaces] fixed docu
[functions.visualization] whitespace
[functions.combined] added difference
[common.convergence-study] added for arbitrary norms/discretizations
[function] moved VisualizationAdapter from default to visualization
[functions.local] removed
[test.test_common] fixed includes and fem namespaces
[functions.interfaces] added possibility for checks
[functions.constant] added checks