tutorials: Remove the unnecessary "\"s on "cp", "rm" and "mv"

Resolves bug-report http://bugs.openfoam.org/view.php?id=2077

tutorials/mesh/foamyHexMesh/mixerVessel/Allrun-simulation

@@ -4,12 +4,12 @@ cd ${0%/*} || exit 1    # Run from this directory
 # Source tutorial run functions
 . $WM_PROJECT_DIR/bin/tools/RunFunctions
 
-\cp system/controlDict.flow system/controlDict
+cp system/controlDict.flow system/controlDict
 
 # Set application name
 application=$(getApplication)
 
-\rm -rf 0
+rm -rf 0
 
 runApplication createBaffles -overwrite
 runApplication mergeOrSplitBaffles -split -overwrite
@@ -18,7 +18,7 @@ runApplication mergeOrSplitBaffles -split -overwrite
 runApplication createPatch -overwrite
 
 # Copy fields after meshing to avoind the generation of unnecessary patch fields
-\cp -r 0.orig 0
+cp -r 0.orig 0
 
 # Initialize alpha
 runApplication setFields