eigen and tbb might've already be discovered by pdelab/common

also promotes all DSC_CONFIG_* macros to real functions #refs 68

GridUtils now default to YaspGrid, which is now also the only
grid implementation guaranteed to be availabe for testing
if dune-grid is present

This reverts commit 72f65d6a8152620741e0292b0f7cbfe95b23b2eb.

by adding a ctor that takes ```vector<string>``` for keys and values
and a utility function in algorithm that allows code re-use

This reverts commit ba71a7857d78f85ff258834f7820928c253102af
since the update required cmake stuff in common (>=2.4)

[common] major Configuration simplification

This should always be the norm as it shows problems with missing
includes early.

- strips away Request mapping and default recording
- removes functionally equivalent constructors and ``get`` variants
- test continue to pass (std::complex still failing) w/o modification
beyond removing calls to removed functionality.
- Esp. ``get`` calls should need no maintenance on the user side

Profiler timing change

which only compiles with gcc atm

New complex<double> tests still fail though.

these have a lot better output on failure than
EXPECT_TRUE(FloatCmp::XX(a,b))

simply uses the same distribution, generator and limits for real and
imaginary parts

and forwards to each Visitor's run(...) accordingly

now with less code, fewer exception throwing and more test coverage ;-)

adds get_delta for retrieving all 3 measured values

The real walltime is now returned and the DeltaType has lost its first
mixed number accordingly. This is not yet an interface change.

closes #63