Add forum link in nav bar an index page (#29)

Include the link with the Discourse icon. Also include links in the
sections of the index page to all other pages, including Github and the
forum. Open external links in new tabs.

Author: leouieda

_templates/navbar.html

@@ -6,7 +6,7 @@
                     <li><a href="{{ pathto(*link[1:]) }}"><strong>{{ link[0] }}</strong></a></li>
                 {%- endfor %}
                 {%- for link in social_links %}
-                    <li><a href="{{ link[2] }}" title="{{ link[1] }}">{{ link[0] }}</a></li>
+                    <li><a href="{{ link[2] }}" title="{{ link[1] }}" target="_blank">{{ link[0] }}</a></li>
                 {%- endfor %}
             </ul>
         {% endif %}

conf.py

@@ -73,9 +73,9 @@
             "https://github.com/GenericMappingTools",
         ),
         (
-            '<i class="fab fa-gitter fa-lg"></i>',
-            "Gitter chat",
-            "https://gitter.im/GenericMappingTools/Lobby",
+            '<i class="fab fa-discourse fa-lg"></i>',
+            "Forum",
+            "https://forum.generic-mapping-tools.org/",
         ),
     ],
     "url": "https://www.generic-mapping-tools.org",

index.rst

@@ -87,10 +87,19 @@
 
             <h2>A toolbox for Earth, Ocean, and Planetary Science</h2>
 
-            GMT is widely used across the Earth, Ocean, and Planetary sciences. A diverse community
-	    use GMT to process data, generate publication-quality illustrations, automate workflows,
-	    and make animations.  Scientific journals, posters at meetings, and Wikipedia pages display
-	    illustrations made by GMT.
+            <p>
+            GMT is widely used across the Earth, Ocean, and Planetary sciences. A
+            diverse community use GMT to process data, generate publication-quality
+            illustrations, automate workflows, and make animations.  Scientific
+            journals, posters at meetings, and Wikipedia pages display illustrations
+            made by GMT.
+            </p>
+            <p>
+            <strong>Want to get involved?</strong>
+            Join the <a href="https://forum.generic-mapping-tools.org/" target="_blank">
+            <i class="fab fa-discourse"></i> GMT Community Forum</a> to ask questions, get help,
+            and connect with other users and developers.
+            </p>
 
             </div>
             <div class="col-sm-5 col-sm-pull-7">
@@ -105,9 +114,21 @@
 
             <h2>Publication quality figures and animations</h2>
 
-            Whether Cartesian, geographic, or time-series, GMT can process your data. GMT enables
-	    you to explore new ways to analyze data and to build custom displays for drafts, publications,
-	    or final presentations.  GMT allows unlimited customization via scripting in several languages.
+            <p>
+            Whether Cartesian, geographic, or time-series, GMT can process your data.
+            GMT enables you to explore new ways to analyze data and to build custom
+            displays for drafts, publications, or final presentations.  GMT allows
+            unlimited customization via scripting in several languages.
+            </p>
+            <p>
+            Visit our <a href="/documentation"> Documentation</a> page to find out all
+            that GMT can do for you.
+            </p>
+            <p>
+            <strong>Used GMT in your research?</strong> Please
+            consider <a href="cite">citing GMT</a> so we can justify the continued
+            development efforts.
+            </p>
 
             </div>
             <div class="col-sm-5">
@@ -183,10 +204,22 @@
 
             <h2>C, MATLAB, Julia, Python</h2>
 
-            GMT has been used from UNIX and Windows command lines for decades.  More recently, GMT
-	    has been rebuilt as an Application Programming Interface (API) and can now be accessed
-	    via wrapper libraries from MATLAB/Octave, Julia, and Python, as well from custom programs
-	    written in C or C++.
+            <p>
+            GMT has been used from UNIX and Windows command lines for decades.  More
+            recently, GMT has been rebuilt as an Application Programming Interface (API)
+            and can now be accessed via wrapper libraries from MATLAB/Octave, Julia, and
+            Python, as well from custom programs written in C or C++.
+            </p>
+            <p>
+            See all the projects the team is working on in the
+            <a href="/projects">Ecosystem</a> page.
+            </p>
+            <p>
+            <strong>Want to see the code?</strong> All development happens through
+            GitHub in our
+            <a href="https://github.com/GenericMappingTools" target="_blank"><i class="fab fa-github"></i>
+            GenericMappingTools account</a>.
+            </p>
 
             </div>
             <div class="col-sm-5 col-sm-pull-7">