New:
---

Pressure boundary conditions for vertical walls added to the multigrid solver.
They are applied using new wall flag arrays (wall_flags_..) which are defined
for each grid level. New argument gls added to routine user_init_grid
(user_interface).

init_grid, init_pegrid, modules, user_interface


Changed:
-------


Errors:
------

Bugfix: pleft/pright changed to pnorth/psouth in sendrecv of particle tail
numbers along y (advec_particles)

Bugfix: model_string needed a default value (combine_plot_fields)

advec_particles, combine_plot_fields