snappyHexMesh for OpenFOAM.

To generate a mesh within a domain defined by a stl file, we can take the following steps:
1. Create the geometry in SALOME, then export the faces into individual stl files.
2. Edit the stl files according to the motorBike case in the tutorial, combine them into a single stl file, and then put it in the folder 'constant/triSurface'.
3. Create the blockMeshDict and leave the patches to be empty, and run blockMesh.
4. Put decomposeParDict and snappyHexMeshDict into the folder 'system', edit snappyHexMeshDict according the motorBike tutorial.
5. Run snappyHexMesh and the mesh will be ready for OpenFOAM.