Fix python wrapper for CPU proxies
The Python example programs did no longer work, most likely because the C wrapper has not been updated to match the std::shared_ptr
used for Proxy::allocate_grid
.
This branch contains a number of fixes/workarounds to make cpu-reference.py and cpu-optimized.py work again.
The example programs that use the CUDA or Hybrid proxies still don't work. This is to be addressed separately.