plugins/router_hash: Avoid possible divide by zero

Reported by Coverity as CID #1100804.
plugins/rpc_plugin: check return value of uwsgi_response_prepare_headers

Reported by Coverity as CID #1100798.
added read errors counters and --log-ioerror
added werr, rerr and ioerr to logvars
report request data in writers and readers
in request context uwsgi_req_error should always be used
added as-mule hook
ported mjpeg stream to newer osx
fixed plain (without suspend engine) async mode
avoid segfault when async mode api is called without async mode
avoid allocating memory structures for fd monitoring and timeouts when non-plain async mode is in place
added S master fifo command
prepare for the new sharedarea api
area is a better field name for sharedarea
another round of sharedarea implementations
allows sharedarea_wait to specify the freq
Merge pull request #468 from xrmx/coverity2911

Coverity Fixes
more sharedarea api functions
added milliseconds wait hook to Coro::AnyEvent
added milliseconds hook support to gevent