Use mesh->n_corners() method.
Added generated file: doc/reference_manual/flow_version.tex to .gitignore.
Removed unused code from output_time.hh
Removed unused code and formating in output_msh.cc
Removed unused code from output_time.cc
Added method virtual method print_all() to OutpuDataBase.

* It prints at once all data in one field.
* It is 2x faster then previous method. For 2 milion of elements
  it takes 5s to write add data. It took 10s for previous solution.
* It is used only by VTK file format. GMSH file format has to use
  old solution.
Refactoring and indentation.