Squashed 'src/beast/' changes from 9f10b11..1b9a714
1b9a714 Set version to 1.0.0-b30
faed9e5 Allow concurrent websocket async ping and writes:
31cda06 Fix race when write suspends
48dd38e Fix race in close frames during reads
e2d1bb0 Fix race in pings during reads
36143be Set version to 1.0.0-b29
f0399b6 Fix doc link typo
787b7c2 Check ostream modifier correctly
4fa0bf6 Fix Writer return value documentation
6406da0 Document type-pun in buffer_cat
66cdb37 Fix illegal HTTP characters accepted as hex zero
e64ca2f Fix Body requirements doc
6dfd9f9 Fix compilation error in non-template class
fa7fea8 Fix race in writes during reads:
git-subtree-dir: src/beast
git-subtree-split: 1b9a71483347b7027b2fb7fe27ecea148d2e79ba