Several documentation enhancements and build warnings fixes

- Made the documentation even more friendly towards newbies.
- Eased the usage of methods like get history which now set
  a default empty message for message actions and vice versa.
- Fixed some docstring documentations too.
- Updated the old normal docs/ to link back and forth RTD.
- Fixed the version of the documentation, now auto-loaded.

docs/res/core.html

@@ -44,8 +44,15 @@
     page aims to provide easy access to all the available methods, their
     definition and parameters.</p>
 
-    <p>Although this documentation was generated for <i>Telethon</i>, it may
-    be useful for any other Telegram library out there.</p>
+    <p>Please note that when you see this:</p>
+    <pre>---functions---
+users.getUsers#0d91a548 id:Vector&lt;InputUser&gt; = Vector&lt;User&gt;</pre>
+
+    <p>This is <b>not</b> Python code. It's the "TL definition". It's
+    an easy-to-read line that gives a quick overview on the parameters
+    and its result. You don't need to worry about this. See
+    <a href="http://telethon.readthedocs.io/en/latest/extra/developing/understanding-the-type-language.html">here</a>
+    for more details on it.</p>
 
     <h3>Index</h3>
     <ul>
@@ -69,12 +76,12 @@
     <p>Currently there are <b>{method_count} methods</b> available for the layer
     {layer}. The complete list can be seen <a href="methods/index.html">here</a>.
     <br /><br />
-    Methods, also known as <i>requests</i>, are used to interact with
-    the Telegram API itself and are invoked with a call to <code>.invoke()</code>.
-    <b>Only these</b> can be passed to <code>.invoke()</code>! You cannot
-    <code>.invoke()</code> types or constructors, only requests. After this,
-    Telegram will return a <code>result</code>, which may be, for instance,
-    a bunch of messages, some dialogs, users, etc.</p>
+    Methods, also known as <i>requests</i>, are used to interact with the
+    Telegram API itself and are invoked through <code>client(Request(...))</code>.
+    <b>Only these</b> can be used like that! You cannot invoke types or
+    constructors, only requests. After this, Telegram will return a
+    <code>result</code>, which may be, for instance, a bunch of messages,
+    some dialogs, users, etc.</p>
 
     <h3 id="types">Types</h3>
     <p>Currently there are <b>{type_count} types</b>. You can see the full
@@ -151,58 +158,9 @@
     </ul>
 
     <h3 id="example">Full example</h3>
-    <p>The following example demonstrates:</p>
-    <ol>
-        <li>How to create a <code>TelegramClient</code>.</li>
-        <li>Connecting to the Telegram servers and authorizing an user.</li>
-        <li>Retrieving a list of chats (<i>dialogs</i>).</li>
-        <li>Invoking a request without the built-in methods.</li>
-    </ol>
-    <pre><span class="sh3">#!/usr/bin/python3</span>
-<span class="sh4">from</span> telethon <span class="sh4">import</span> TelegramClient
-<span class="sh4">from</span> telethon.tl.functions.messages <span class="sh4">import</span> GetHistoryRequest
-
-<span class="sh3"># <b>(1)</b> Use your own values here</span>
-api_id   = <span class="sh1">12345</span>
-api_hash = <span class="sh2">'0123456789abcdef0123456789abcdef'</span>
-phone    = <span class="sh2">'+34600000000'</span>
-
-<span class="sh3"># <b>(2)</b> Create the client and connect</span>
-client = TelegramClient(<span class="sh2">'username'</span>, api_id, api_hash)
-client.connect()
-
-<span class="sh3"># Ensure you're authorized</span>
-if not client.is_user_authorized():
-    client.send_code_request(phone)
-    client.sign_in(phone, input(<span class="sh2">'Enter the code: '</span>))
-
-<span class="sh3"># <b>(3)</b> Using built-in methods</span>
-dialogs, entities = client.get_dialogs(<span class="sh1">10</span>)
-entity = entities[<span class="sh1">0</span>]
-
-<span class="sh3"># <b>(4)</b> !! Invoking a request manually !!</span>
-result = <b>client</b>(GetHistoryRequest(
-    entity,
-    limit=<span class="sh1">20</span>,
-    offset_date=<span class="sh1">None</span>,
-    offset_id=<span class="sh1">0</span>,
-    max_id=<span class="sh1">0</span>,
-    min_id=<span class="sh1">0</span>,
-    add_offset=<span class="sh1">0</span>
-))
-
-<span class="sh3"># Now you have access to the first 20 messages</span>
-messages = result.messages</pre>
-
-    <p>As it can be seen, manually calling requests with
-    <code>client(request)</code> (or using the old way, by calling
-    <code>client.invoke(request)</code>) is way more verbose than using the
-    built-in methods (such as <code>client.get_dialogs()</code>).</p>
-
-    <p>However, and
-    given that there are so many methods available, it's impossible to provide
-    a nice interface to things that may change over time. To get full access,
-    however, you're still able to invoke these methods manually.</p>
+    <p>Documentation for this is now
+    <a href="http://telethon.readthedocs.io/en/latest/extra/advanced-usage/accessing-the-full-api.html">here</a>.
+    </p>
 </div>
 
 </div>