Synchronization

[ProGTX]

Already mentioned in #6

Parts to implement per §2.5.5:

• ⚠️ Buffer destruction
  • ✅ Wait on events in destructor
  • 🔴 Asynchronous error handling #9, copying, smart pointers
• ✅ Accessor construction
  • ✅ Device accessors
    • Through Asynchronous kernels #14
  • ✅ Host accessors
• ✅ Command group enqueue
  • Asynchronous kernels #14
• ⚠️ Interaction with OpenCL synchronization operations
  • I'm not sure what this is supposed to entail with regard to buffer and image. Maybe mutex?
  • ⚠️ handler_event from queue.
• ✅ Queue destruction
• ⚠️ Context destruction
  • Not high priority, problems with copies and moves.
• ⚠️ SYCL event objects
  • 🔴 Asynchronous error handling #9

[ProGTX]

"Command group enqueue", or intra-queue synchronization, was done alongside #14.

[ProGTX]

Host accessors synchronized with synchronizer class (see #1).

[ProGTX]

Forgot to take into account that host accessors block the queue for their whole lifetime, and just synchronization on construction isn't enough. Fixed in d25b7f5.