and writes. This was previously unsafe because we almost always passed read/write
buffers to boost that were on the stack. Canceling the task deleted the stack and
therefore the buffer, but couldn't reliably prevent boost from writing to the buffer
if data came in after the cancel. This commit adds variants of the read and write
functions that take a shared_ptr<char> instead of a raw char* as the buffer, and
these variants will ensure the shared_ptr will outlive the boost::asio read/write.
Restructure udp_socket::receive_from() to something functionally identical, but has one less exception handler on the stack which I hope would make it easier to debug strange exception-handling errors encountered on win64
Re-organize read-loop execution to avoid crashes in read_loop on Win32 when ntp object destructs. Call quit on ntp_thread when ntp object destructs to free up thread (eventually we need to make fc::threads call quit in their destructor, but more work is required to make that work properly).
~fc::udp_socket now closes socket on destruction (consider doing this for tcp sockets as well).