This allows the client stuff to understand that addresses beginning with '+'
represent unix sockets.
If the first character after the '+' is '@', it understands that the '@'
should be read as '\0', in order to use Linux "abstract namespace"
sockets.
Further the lws_parse_uri() helper is extended to understand the convention
that an address starting with + is a unix socket, and treats the socket
path as delimited by ':', eg
http://+/var/run/mysocket:/my/path
HTTP Proxy is updated to allow mounts to these unix socket paths.
Proxy connections go out on h1, but are dynamically translated to h1 or h2
on the incoming side.
Proxy usage of libhubbub is separated out... LWS_WITH_HTTP_PROXY is on by
default, and LWS_WITH_HUBBUB is off by default.
This has no effect on user code or backward compatibility.
It moves the in-tree public api header libwebsockets.h from ./lib
to ./include, and introduces a dir ./include/libwebsockets/
The single public api header is split out into 31 sub-headers
in ./include/libwebsockets. ./include/libwebsockets.h contains
some core types and platform adaptation code, but the rest of it
is now 31 #include <libwebsockets/...>
At install time, /usr/[local/]include/libwebsockets.h is installed
as before, along now with the 31 sub-headers in ...include/libwebsockets/
There's no net effect on user code.
But the api header is now much easier to maintain and study, with 31
topic-based sub headers.
