Write a nice new man page in AsciiDoc

Taking some preliminary steps for inclusion in Linux distributions.

The help message has been slightly improved and the README extended,
with part of it now residing in the man page.

One less GNU dependency, for what it's worth.

README.adoc

@@ -17,38 +17,28 @@ you get the following niceties:
  - ability to pipe output through a shell command, so that you can view the
    results in your favourite editor or redirect them to a file
  - ability to edit the input line in your favourite editor as well with Alt+E
+ - WebSockets (RFC 6455) can also be used as a transport rather than HTTP
 
-Supported transports
---------------------
- - HTTP
- - HTTPS
- - WebSocket
- - WebSocket over TLS
-
-WebSockets
-~~~~~~~~~~
-The JSON-RPC 2.0 spec doesn't say almost anything about underlying transports.
-The way it's implemented here is that every request is sent as a single text
-message.  If it has an "id" field, i.e. it's not just a notification, the
-client waits for a message from the server in response.
-
-There's no support so far for any protocol extensions, nor for specifying
-the higher-level protocol (the "Sec-Ws-Protocol" HTTP field).
+Documentation
+-------------
+See the link:json-rpc-shell.adoc[man page] for information about usage.
+The rest of this README will concern itself with externalities.
 
 Packages
 --------
 Regular releases are sporadic.  git master should be stable enough.  You can get
 a package with the latest development version from Archlinux's AUR.
 
-Building and Usage
-------------------
-Build dependencies: CMake, pkg-config, help2man,
+Building
+--------
+Build dependencies: CMake, pkg-config, asciidoctor,
                     liberty (included), http-parser (included) +
 Runtime dependencies: libev, Jansson, cURL, openssl,
                       readline or libedit >= 2013-07-12,
 
 Avoid libedit if you can, in general it works but at the moment history is
-acting up and I have no clue about fixing it.
+acting up and I have no clue about fixing it.  Multiline editing is also
+misbehaving there.
 
  $ git clone --recursive https://git.janouch.name/p/json-rpc-shell.git
  $ mkdir json-rpc-shell/build
@@ -68,13 +58,12 @@ Or you can try telling CMake to make a package for you.  For Debian it is:
 Note that for versions of CMake before 2.8.9, you need to prefix `cpack` with
 `fakeroot` or file ownership will end up wrong.
 
-Run the program with `--help` to obtain usage information.
-
 Test server
 -----------
 If you install development packages for libmagic, an included test server will
 be built but not installed which provides a trivial JSON-RPC 2.0 service with
-FastCGI, SCGI, and WebSocket interfaces.  It responds to the `ping` method.
+FastCGI, SCGI, and WebSocket interfaces.  It responds to `ping` and `date`
+methods and it can serve static files.
 
 Contributing and Support
 ------------------------