[CPU] Fix python bindings.

Closes #103

CMake/VirtualFluidsMacros.cmake

@@ -246,8 +246,8 @@ function(vf_add_library)
     target_include_directories(${library_name} PUBLIC ${CMAKE_CURRENT_SOURCE_DIR})
     target_include_directories(${library_name} PRIVATE ${CMAKE_BINARY_DIR})
     target_include_directories(${library_name} PRIVATE ${VF_SRC_DIR})
-    target_include_directories(${library_name} PRIVATE ${VF_SRC_DIR}/gpu)
-    target_include_directories(${library_name} PRIVATE ${VF_SRC_DIR}/cpu)
+    target_include_directories(${library_name} PUBLIC ${VF_SRC_DIR}/gpu)
+    target_include_directories(${library_name} PUBLIC ${VF_SRC_DIR}/cpu)
 
     if(BUILD_VF_GPU)
         target_include_directories(${library_name} PRIVATE "${VF_THIRD_DIR}/cuda_samples/")