Solvers and tutorials: changed use of buoyantPressure BC to fixedFluxPressure

...ications/solvers/multiphase/interFoam/interDyMFoam/pEqn.H

applications/solvers/multiphase/settlingFoam/pEqn.H

...als/combustion/fireFoam/les/oppositeBurningPanels/0/p_rgh

tutorials/combustion/fireFoam/les/smallPoolFire2D/0/p_rgh

tutorials/combustion/fireFoam/les/smallPoolFire3D/0/p_rgh

.../heatTransfer/buoyantBoussinesqPimpleFoam/hotRoom/0/p_rgh

.../heatTransfer/buoyantBoussinesqSimpleFoam/hotRoom/0/p_rgh

...sfer/buoyantBoussinesqSimpleFoam/iglooWithFridges/0/p_rgh

tutorials/heatTransfer/buoyantPimpleFoam/hotRoom/0/p_rgh

...ials/heatTransfer/buoyantSimpleFoam/buoyantCavity/0/p_rgh

...ransfer/buoyantSimpleFoam/circuitBoardCooling/0.org/p_rgh

tutorials/heatTransfer/buoyantSimpleFoam/hotRoom/0/p_rgh

...nsfer/buoyantSimpleRadiationFoam/hotRadiationRoom/0/p_rgh

.../buoyantSimpleRadiationFoam/hotRadiationRoomFvDOM/0/p_rgh

...ible/pimpleFoam/elipsekkLOmega/constant/polyMesh/boundary

...ls/lagrangian/reactingParcelFilmFoam/cylinder/0.org/p_rgh

...ls/lagrangian/reactingParcelFilmFoam/hotBoxes/0.org/p_rgh

...agrangian/reactingParcelFilmFoam/rivuletPanel/0.org/p_rgh

...lagrangian/reactingParcelFilmFoam/splashPanel/0.org/p_rgh

tutorials/multiphase/LTSInterFoam/wigleyHull/0/p_rgh