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)

There is shor test of this stuff for 1D 2D and 3D.

Relpaced tabs with 4spaces.

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