- although this has been supported for many years, the tutorials
continued to use "convertToMeters" entry, which is specific to blockMesh.
The "scale" is more consistent with other dictionaries.
ENH:
- ignore "scale 0;" (treat as no scaling) for blockMeshDict,
consistent with use elsewhere.
For multi-region cases the default location of blockMeshDict is now system/<region name>
If the blockMeshDict is not found in system then the constant directory
is also checked providing backward-compatibility
