regression from 942d0c6

the script always returned 1.11.0-rc1, because apparently that tag
was annotated, unlike the newer ones.

this could lead to a DoS when a legitimate client reads from an
attacker-controlled web server.

closes tinyproxy#597

due to some ancient piece of code that's supposed to fix a bug
in 1990's internet explorer, sockets were switched between blocking
and non-blocking mode, making it hard to differentiate when
socket timeouts kicked in.

with the IE bug workaround removed, sockets are now always in
blocking mode so we no longer need to catch EAGAIN/EWOULDBLOCK
and treat them specially, they are now always treated as an
error (whenever they are returned, the timeout kicked in).

this should fix once and for all the cases where tinyproxy
would not respect the user-provided socket timeouts, potentially
causing endless loops.

closes tinyproxy#598

…roxy#603)

follow-up to 969852c

closes tinyproxy#602

the chunked transfer encoding needs to be matched in a case-
insensitive manner.

closes tinyproxy#604

until now, only the basicauth code checked the host header, regular connections didn't.

- add a new helper function to compare a hostname with optional 
  trailingcolon/port against the stathost.
- add stathost check via host header before transparent proxy check,
  else stathost might be misdetected as a trans host request.
- refactor existing stathost checks to use the new helper

this should make it easier to access the stathost, for example by
injecting a host header into a curl command line with -H:

    $ curl -H "Host: tinyproxy.stats" 127.0.0.1:8080

the stathost can also be specified as an ip address, e.g.
Stathost "127.0.0.10" + a separate Listen statement for that ip.
in such a case e.g.

    $ curl http://127.0.0.10:8080

would work too, even if curl didn't add a Host header (but it does anyway).