Add examples on how to send messages to rooms

This adds two similar examples, one using matrix.client, and the other using
matrix.api.

README.md

@@ -69,9 +69,11 @@ api:send_text(response.room_id, "Hello!")
 For the low-level `matrix.api`:
 
 * [examples/set-display-name.lua](./examples/set-display-name.lua)
+* [examples/api-send-message.lua](./examples/api-send-message.lua)
 
 For the high-level `matrix.client`:
 
 * [examples/get-user-info.lua](./examples/get-user-info.lua)
+* [examples/client-send-message.lua](./examples/client-send-message.lua)
 
 More examples can be found in the [examples](./examples) subdirectory.

examples/api-send-message.lua

@@ -0,0 +1,18 @@
+#! /usr/bin/env lua
+--
+-- api-send-message.lua
+-- Copyright (C) 2016 Adrian Perez <aperez@igalia.com>
+--
+-- Distributed under terms of the MIT license.
+--
+
+if #arg ~= 4 then
+   io.stderr:write(string.format("Usage: %s <homeserver-URL> <username> <password> <room>\n", arg[0]))
+   os.exit(1)
+end
+
+local api = require "matrix" .api(arg[1])
+local response = api:login("m.login.password", { user = arg[2], password = arg[3] })
+api.token = response.access_token
+api:send_message(arg[4], io.read("*a"))
+api:logout()

examples/client-send-message.lua

@@ -0,0 +1,24 @@
+#! /usr/bin/env lua
+--
+-- send-message.lua
+-- Copyright (C) 2016 Adrian Perez <aperez@igalia.com>
+--
+-- Distributed under terms of the MIT license.
+--
+
+if #arg ~= 4 then
+   io.stderr:write(string.format("Usage: %s <homeserver-URL> <username> <password> <room>\n", arg[0]))
+   os.exit(1)
+end
+
+local client = require "matrix" .client(arg[1])
+client:login_with_password(arg[2], arg[3])
+
+-- FIXME: This does not resolve room aliases, it works only with room IDs
+local room = client.rooms[arg[4]]
+if not room then
+   room = client:join_room(arg[4])
+end
+
+room:send_text(io.read("*a"))
+client:logout()