multiphaseEulerFoam: replacement for reactingMultiphaseEulerFoam

The new multiphaseEulerFoam is based on reactingMultiphaseEulerFoam with some
improvements and rationalisation to assist maintenance and further development.

The phase system solution has been enhanced to handle two phases more
effectively and all two-phase specific models updated for compatibility so that
multiphaseEulerFoam can also replace reactingTwoPhaseEulerFoam.
When running multiphaseEulerFoam with only two-phases the default behaviour is
to solve for both phase-fractions but optionally a reference phase can be
specified so that only the other phase-fraction is solved, providing better
compatibility with the behaviour of reactingTwoPhaseEulerFoam.

All reactingMultiphaseEulerFoam and reactingTwoPhaseEulerFoam tutorials have
been updated for multiphaseEulerFoam.

tutorials/multiphase/multiphaseEulerFoam/RAS/bubblePipe/Allrun

@@ -0,0 +1,14 @@
+#!/bin/sh
+cd ${0%/*} || exit 1    # run from this directory
+
+# Source tutorial run functions
+. $WM_PROJECT_DIR/bin/tools/RunFunctions
+
+application=`getApplication`
+
+runApplication blockMesh
+runApplication extrudeMesh
+runApplication $application
+( cd validation && ./createGraphs )
+
+#------------------------------------------------------------------------------