Fixed handling of the boundary conditions for explicit solver - introduced a method Problem::applyBoundaryConditions.

Only MPICommunicator and DistributedGrid is implemented.

Allow existance of non setup synchronizer object. MeshFunction creates grid synchronizer automagicli with binding.
(only if distr grid was chnged)

For compatibility with unported examples, the old typedef is still kept,
but IndexType should be removed from grids eventually.

Adding Gnuplot writer for vector field.

I think this is much better because even operators inherit from Domain
and operator.getDimensions() is very confusing.

	Seriove
	jen 2D
	používá pomalé operace: pass to MIC, free from MIC

Dále asi nepujde zkompilovat celé TNL, kvuli __cuda_callable__ == __device_callable__ a nezakrytí MIC částí kódu pomocí HAVE_MIC.