This avoids irritating warnings of wmake about it not finding certain headers
(e.g. system headers). Similar things were necessary in some headers of the
LIGGGHTS code. While these did not cause compilation errors, they messed up
the compilation output with hundrets of false alarms. Not very helpful if
you're trying to find out what went wrong.
One special case is the change from RASModel.H to turbulenceModel.H in
cfdemCloud.H. Between major OpenFOAM versions there was a change of how
turbulence models were implemented. While the CFDEMcoupling code uses
preprocessors to allow compatibility, the wmkdepend utility is too simple
to understand this. It does not evaluate #ifdef constructs and just looks
for #include lines. Therefore it tries to access RASModel.H in newer
versions of OpenFOAM, which no longer exists.
To circumvent this issue, both includes were changed from "" to <> syntax.
This suppresses the warning and compiles, since the OpenFOAM header is in
the include path anyway.
