Pybind11

• Investigate what's wrong with the CIs
• Switch to pybind11 Python package instead of submodule
• Make sure the docs build (semi-)identically
• CL2 get_info/constants
• SVM
• DeviceTopologyAmd
• UserEvent callbacks
• clCreateSampler
• clCreateCommandQueueWithProperties
• Adapt, test loopy
• Pytential/boxtree tests pass: boxtree!58 (closed), pytential!129 (closed)
• Pypy compilation
• Solicit community feedback
• Remove set_callback instrumentation