Enabling Cascade module fails when no CASCADE_INCLUDE_DIR is set

[yurivict]

-- ==== Chrono Cascade module ====
CMake Error at src/chrono_cascade/CMakeLists.txt:92 (IF):
  if given arguments:

    "NOT" "EXISTS" "OR" "NOT" "EXISTS"

  Unknown arguments specified

This is a bug in cmake files. It should test or quote the strings.

It should also have cmake find opencascade because opencascade provides cmake files.

[rserban]

Thanks for pointing out that issue in CMakeLists. I fixed it and included it in the amended 6.0.0 release.

We will look at using the opencascade cmake project configuration script to properly find that dependency.
If you would create a PR for this, that would be great!