Boundary WIP, kinda works but get small errors and fluid behaves a bit...

Boundary with static boundary particles

src/cuda/include/cuda_device_vars.h

@@ -57,7 +57,7 @@ extern float* d_sum_gradW2; // For computing A
 
 // Boundary particles
 extern float3* d_boundary_positions;
-extern float3* d_boundary_velocities;
+extern float3* d_boundary_normals;
 
 extern unsigned int* d_boundaryCellStart;
 extern unsigned int* d_boundaryCellEnd;