OpenFAST Configuration file

[sayerhs]

This commit creates an OpenFASTConfig.cmake file that can be used to detect a valid OpenFAST install and configure library linking automatically. The design follows Trilinos setup closely and can be used in a similar manner in Nalu's CMakeLists.txt

if (NALU_USES_OpenFAST)
    SET(CMAKE_PREFIX_PATH ${OpenFAST_DIR} ${CMAKE_PREFIX_PATH})
    find_package(OpenFAST REQUIRED)
endif()

and then in the linking step

if (NALU_USES_OpenFAST)
   target_link_libraries(naluX ... ${OpenFAST_LIBRARIES})
endif()

To use this, one has to make install the compile OpenFAST into a central location (similar to Trilinos).