cavitationModels: Made insensitive to phase order

The cavitation models used by the interFoam solver and the
compressibleVoF solver module can now be applied regardless of the
ordering of the liquid and vapour phases. A "liquid" keyword is now
required in the model specification in order to control which phase is
considered to be the condensed liquid state. Previously the liquid phase
was assumed to be the first of the two phases.

tutorials/multiphase/interFoam/RAS/propeller/constant/fvModels

@@ -26,6 +26,8 @@ VoFCavitation
     {
         pSat    2300;   // Saturation pressure
 
+        liquid  water;
+
         UInf    20.0;
         tInf    0.005; // L = 0.1 m
         Cc      1000;
@@ -36,6 +38,8 @@ VoFCavitation
     {
         pSat    2300;   // Saturation pressure
 
+        liquid  water;
+
         UInf    20.0;
         tInf    0.005;  // L = 0.1 m
         Cc      80;
@@ -46,6 +50,8 @@ VoFCavitation
     {
         pSat    2300;   // Saturation pressure
 
+        liquid  water;
+
         n       1.6e+13;
         dNuc    2.0e-06;
         Cc      1;

tutorials/multiphase/interFoam/laminar/cavitatingBullet/constant/fvModels

@@ -26,6 +26,8 @@ VoFCavitation
     {
         pSat    2300;   // Saturation pressure
 
+        liquid  water;
+
         UInf    20.0;
         tInf    0.005; // L = 0.1 m
         Cc      1000;
@@ -36,6 +38,8 @@ VoFCavitation
     {
         pSat    2300;   // Saturation pressure
 
+        liquid  water;
+
         UInf    20.0;
         tInf    0.005;  // L = 0.1 m
         Cc      80;
@@ -46,6 +50,8 @@ VoFCavitation
     {
         pSat    2300;   // Saturation pressure
 
+        liquid  water;
+
         n       1.6e+13;
         dNuc    2.0e-06;
         Cc      1;