OpenFOAM field reading: Automated the handling of <field>.orig files

Now if a <field> file does not exist first the compressed <field>.gz file is
searched for and if that also does not exist the <field>.orig file is searched
for.

This simplifies case setup and run scripts as now setField for example can read
the <field>.orig file directly and generate the <field> file from it which is
then read by the solver.  Additionally the cleanCase function used by
foamCleanCase and the Allclean scripts automatically removed <field> files if
there is a corresponding <field>.orig file.  So now there is no need for the
Allrun scripts to copy <field>.orig files into <field> or for the Allclean
scripts to explicitly remove them.

tutorials/incompressible/simpleFoam/motorBike/Allclean

@@ -9,8 +9,6 @@ rm -f constant/triSurface/motorBike.obj.gz > /dev/null 2>&1
 rm -rf constant/extendedFeatureEdgeMesh > /dev/null 2>&1
 rm -f constant/triSurface/motorBike.eMesh > /dev/null 2>&1
 
-rm -rf 0 > /dev/null 2>&1
-
 cleanCase
 
 #------------------------------------------------------------------------------

tutorials/incompressible/simpleFoam/motorBike/Allrun

@@ -10,8 +10,6 @@ runApplication surfaceFeatureExtract
 
 runApplication blockMesh
 
-[ ! -d 0 ] && cp -r 0.orig 0
-
 runApplication decomposePar -copyZero
 runParallel snappyHexMesh -overwrite