back port uninitialized variable access fix from libtorrent_aio
use posix_memalign on linux, not valloc
make disk cache pool allocator configurable
fix disk setting sync.
reduce direct use of policy (outside of torrent)
rename perform_async_job to just perform_job
merged fix from RC_0_16
some fixes to when failing to flush a block to disk
merged changes from trunk
add debug logging for do_clear_piece assert
fix type issue in allocator
fix configuration define issue
fix cast issue
allow peers to request bandwidth from the rate limiter and send/receive data at the same time, to cause less stalling when rate limited
remove rate limiter assert
print assert debug information to the same file as the assert itself
fix linux build issue
remove invalid assert
optimized rate limiter by allowing peers to request more bandwidth while waiting on the socket
significantly extend the logging when asserts fire in disk_io_thread or block_cache