* fixes to restart a simulation on refined grid....
* undoing last (inconsistent) commit... (sry for that)
*f_Gamma.json: Remove unused parameters.
*Rematerialize dot which got mis-merged at 93332a9a750c2cc453935a4a67f377ef981e4c76.
*LGPL-Header zugefuegt.
*all MGBuilderCL: build --> build_ser_impl
*MGBuilderCL: -build_par_impl: New, the default action of the Empty*BuilderCL::build.
    -build: Non-virtual: Calls build_ser_impl or build_par_impl depending on MASTER.
    -parnumLevel_, set_par_numlevel: New, to preserve a single
     test in partests/dist_TestRefPar. This should be removed.
*ReadMeshBuilder: Customized build_par_impl.
*builder.{h,cpp}: Remove all Empty...BuilderCL.
*Adapt and simplify all users.
*partests/dist_migration.cpp: sf --> sft to fix pre-existing build-error.
*DROPSParamErrCL: Von DROPSErrCL abgeleitet, um gezielt Fehler von ParamCL abfangen zu koennen.
*ParamCL (std::string), read_json(std::string): ParamCL aus Datei lesen.
*ParamCL::open: Unbenutzt, daher entfernt.
*ParamCL::get<DROPS::SArrayCL<Uint, 3> >: neu, fuer spaeter.
*read_parameter_file_from_cmdline: Liest Parameterdateien, die auf der Kommandozeile gegeben werden.
*In allen Executables, die ParamCL einlesen verwendet.
*make_MGBuilder: Factory for MGBuilderCL-objects as specified in a parameter-file.
*BuilderMap: SingletonMapCL for storing the factory-methods of the subclasses of MGBuilderCL.
*ReadMeshBuilderCL: Additional constructor which takes a filename.
*FileBuilderCL: The class can optionally delete its boundary-builder.
*geom/CMakeLists.txt: misc-params is a dependency of geom-builder.
*tests/{meshreader,serialization,f_Gamma}.cpp: Converted to new mesh-specification to test some important cases.

*This is joint work with Jens Berger.
*get_child: Provisions for better error handling.
*num/bndData.cpp: New, will acquire more content soon.
*Add dependencies on num-bndData.
*bndData.h: -Remove (cyclic) dependency on multigrid.h; depend on simplex.h.
    -Reformat BndCondT-layout.
*Move the periodic-matching function from IdxDescCL to BndCondCL.

*BndCondCL: -mfun_: The matching function for these boundary-data.
    -Get/SetMatchingFunction: Getter/Setter.
    -Init: Initialize all members.
*BndDataCL::Init: Initialize base and all members.
*IdxDescCL: -Remove match_, use Bnd_.GetMatchingFunction().
    -GetMatchFun: Unused --> removed.
*CreatePeriodicNumbOnSimplex: -Remove argument match...
    -...get match from BndDataCL,
    -assert that there is a matching function.
*string_to_BndCondT: Convert string to BndCondT-value.
*read_BndData: Initialize a BndDataCL<T>-object from a parameter-file.
*f_Gamma: Example-usage.
*IdxDescCL::CreateNumbering: -Move all definitions to problem.cpp.
    -Set the matching function only if it is not 0.
*read_BndData: Correct reading of PeriodicMatching.
*BoundaryCL: Simplify memory-management of BndType_.
*read_BndData: Improve Documentation; do not read a matching function if PeriodicMatching is "".
*read_PeriodicBoundaries: Read specification of periodic boundaries of a MultiGridCL-object from a parameter-file.
*TwoPhaseVTKCL, TwoPhaseTransportVTKCL: Incomplet and unused... removed.
*tests/show_domain: VTK-output of a domain; the boundary is colored with the boundary segment number.