refineMesh: Rationalised and standardised the coordinate axes naming to e1, e2 and e3

the previous naming tan1, tan2, normal was non-intuitive and very confusing.

It was not practical to maintain backward compatibility but all tutorials and
example refineMeshDict files have been updated to provide examples of the
change.

tutorials/mesh/refineMesh/refineFieldDirs/system/refineMeshDict.range1

@@ -27,17 +27,17 @@ set range1;
 coordinateSystem fieldBased;
 
 // .. and its coefficients. x,y in this case. (normal direction is calculated
-// as tan1^tan2)
+// as e1  ^e2  )
 globalCoeffs
 {
-    tan1 (1 0 0);
-    tan2 (0 1 0);
+    e1      (1 0 0);
+    e2      (0 1 0);
 }
 
 patchLocalCoeffs
 {
-    patch maxX;  // Normal direction is facenormal of zero'th face of patch
-    tan1 (1 -1 0);
+    patch   maxX;  // Normal direction is facenormal of zero'th face of patch
+    e1      (1 -1 0);
 }
 
 // List of directions to refine

tutorials/mesh/refineMesh/refineFieldDirs/system/refineMeshDict.range2

@@ -27,17 +27,17 @@ set range1;
 coordinateSystem fieldBased;
 
 // .. and its coefficients. x,y in this case. (normal direction is calculated
-// as tan1^tan2)
+// as e1  ^e2  )
 globalCoeffs
 {
-    tan1 (1 0 0);
-    tan2 (0 1 0);
+    e1       (1 0 0);
+    e2       (0 1 0);
 }
 
 patchLocalCoeffs
 {
-    patch maxX;  // Normal direction is facenormal of zero'th face of patch
-    tan1 (1 -1 0);
+    patch     maxX;  // Normal direction is facenormal of zero'th face of patch
+    e1        (1 -1 0);
 }
 
 // List of directions to refine

tutorials/mesh/refineMesh/refineFieldDirs/system/refineMeshDict.range3

@@ -27,17 +27,17 @@ set range1;
 coordinateSystem fieldBased;
 
 // .. and its coefficients. x,y in this case. (normal direction is calculated
-// as tan1^tan2)
+// as e1  ^e2  )
 globalCoeffs
 {
-    tan1 (1 0 0);
-    tan2 (0 1 0);
+    e1      (1 0 0);
+    e2      (0 1 0);
 }
 
 patchLocalCoeffs
 {
-    patch maxX;  // Normal direction is facenormal of zero'th face of patch
-    tan1 (1 -1 0);
+    patch   maxX;  // Normal direction is facenormal of zero'th face of patch
+    e1      (1 -1 0);
 }
 
 // List of directions to refine

tutorials/mesh/refineMesh/refineFieldDirs/system/refineMeshDict.tier1

@@ -26,23 +26,23 @@ coordinateSystem global;
 //coordinateSystem patchLocal;
 
 // .. and its coefficients. x,y in this case. (normal direction is calculated
-// as tan1^tan2)
+// as e1  ^e2  )
 globalCoeffs
 {
-    tan1 (1 0 0);
-    tan2 (0 1 0);
+    e1     (1 0 0);
+    e2     (0 1 0);
 }
 
 patchLocalCoeffs
 {
-    patch outside;  // Normal direction is facenormal of zero'th face of patch
-    tan1 (1 0 0);
+    patch   outside;  // Normal direction is facenormal of zero'th face of patch
+    e1      (1 0 0);
 }
 
 // List of directions to refine
 directions
 (
-    normal
+    e3
 );
 
 // Whether to use hex topology. This will

tutorials/mesh/refineMesh/refineFieldDirs/system/refineMeshDict.tier2

@@ -26,23 +26,23 @@ coordinateSystem global;
 //coordinateSystem patchLocal;
 
 // .. and its coefficients. x,y in this case. (normal direction is calculated
-// as tan1^tan2)
+// as e1  ^e2  )
 globalCoeffs
 {
-    tan1 (1 0 0);
-    tan2 (0 1 0);
+    e1      (1 0 0);
+    e2      (0 1 0);
 }
 
 patchLocalCoeffs
 {
-    patch outside;  // Normal direction is facenormal of zero'th face of patch
-    tan1 (1 0 0);
+    patch   outside;  // Normal direction is facenormal of zero'th face of patch
+    e1      (1 0 0);
 }
 
 // List of directions to refine
 directions
 (
-    normal
+    e3
 );
 
 // Whether to use hex topology. This will

tutorials/mesh/refineMesh/refineFieldDirs/system/refineMeshDict.tier3

@@ -26,23 +26,23 @@ coordinateSystem global;
 //coordinateSystem patchLocal;
 
 // .. and its coefficients. x,y in this case. (normal direction is calculated
-// as tan1^tan2)
+// as e1  ^e2  )
 globalCoeffs
 {
-    tan1 (1 0 0);
-    tan2 (0 1 0);
+    e1      (1 0 0);
+    e2      (0 1 0);
 }
 
 patchLocalCoeffs
 {
-    patch outside;  // Normal direction is facenormal of zero'th face of patch
-    tan1 (1 0 0);
+    patch   outside;  // Normal direction is facenormal of zero'th face of patch
+    e1      (1 0 0);
 }
 
 // List of directions to refine
 directions
 (
-    normal
+    e3
 );
 
 // Whether to use hex topology. This will

tutorials/mesh/refineMesh/refineFieldDirs/system/refineMeshDict.tier4

@@ -26,23 +26,23 @@ coordinateSystem global;
 //coordinateSystem patchLocal;
 
 // .. and its coefficients. x,y in this case. (normal direction is calculated
-// as tan1^tan2)
+// as e1  ^e2  )
 globalCoeffs
 {
-    tan1 (1 0 0);
-    tan2 (0 1 0);
+    e1      (1 0 0);
+    e2      (0 1 0);
 }
 
 patchLocalCoeffs
 {
-    patch outside;  // Normal direction is facenormal of zero'th face of patch
-    tan1 (1 0 0);
+    patch   outside;  // Normal direction is facenormal of zero'th face of patch
+    e1      (1 0 0);
 }
 
 // List of directions to refine
 directions
 (
-    normal
+    e3
 );
 
 // Whether to use hex topology. This will

tutorials/mesh/refineMesh/refineFieldDirs/system/refineMeshDict.tier5

@@ -26,23 +26,23 @@ coordinateSystem global;
 //coordinateSystem patchLocal;
 
 // .. and its coefficients. x,y in this case. (normal direction is calculated
-// as tan1^tan2)
+// as e1  ^e2  )
 globalCoeffs
 {
-    tan1 (1 0 0);
-    tan2 (0 1 0);
+    e1      (1 0 0);
+    e2      (0 1 0);
 }
 
 patchLocalCoeffs
 {
-    patch outside;  // Normal direction is facenormal of zero'th face of patch
-    tan1 (1 0 0);
+    patch   outside;  // Normal direction is facenormal of zero'th face of patch
+    e1      (1 0 0);
 }
 
 // List of directions to refine
 directions
 (
-    normal
+    e3
 );
 
 // Whether to use hex topology. This will

tutorials/mesh/refineMesh/refineFieldDirs/system/refineMeshDict.tier6

@@ -26,23 +26,23 @@ coordinateSystem global;
 //coordinateSystem patchLocal;
 
 // .. and its coefficients. x,y in this case. (normal direction is calculated
-// as tan1^tan2)
+// as e1  ^e2  )
 globalCoeffs
 {
-    tan1 (1 0 0);
-    tan2 (0 1 0);
+    e1      (1 0 0);
+    e2      (0 1 0);
 }
 
 patchLocalCoeffs
 {
-    patch outside;  // Normal direction is facenormal of zero'th face of patch
-    tan1 (1 0 0);
+    patch   outside;  // Normal direction is facenormal of zero'th face of patch
+    e1      (1 0 0);
 }
 
 // List of directions to refine
 directions
 (
-    normal
+    e3
 );
 
 // Whether to use hex topology. This will