[common] drops seperate dune-fem implementation in threadmanager
[fem] adds handy WITH_DUNE_FEM(expression) macro
[common] fixes threaded crtp check macro usage
[cmake] removes unused c++11 checks
[grid.walker] unify tbb usage
[grid.walker] moved tbb stuff from gdt completely

expands tests too
[test] default to std::thread::hardware_concurrency max_threads
[grid.walker] fixes missing TBB includes outside EXADUNE
[test] mini grid element getter
[common.configuration] removes deprecated functions
[common.parallel] splits *ThreadValue into sep. file
[common.parallel] rewire ThreadManager singleton usage
[common.parallel] also set thread count for Eigen
[grid.walker] re-adds functor clearing that was lost in TBB changes
[grid.walker] re-adds another missing functor clear
[grid.walker] allow tweaking partion numbers of default partitioning
[test.la_container] fix some float-equal warnings
[la.container.eigen.base/sparse] add missing includes