Major doc cleanup:

- Reformat source so it's wrapped.
- Standardise markup.
- Center images.
- Restructure in various places to improve the indexing.
- Remove duplicated Query Tool toolbar descriptions.
- Ensure the structure works in both HTML and LaTeX.

docs/en_US/coding_standards.rst

@@ -8,7 +8,7 @@ pgAdmin uses multiple technologies and multiple languages, each of which have
 their own coding standards.
 
 General
-=======
+*******
 
 In all languages, indentations should be made with 4 spaces, and excessively long
 lines wrapped where appropriate to ensure they can be read on smaller displays
@@ -20,7 +20,7 @@ Comments should be included in all code where required to explain its
 purpose or how it works if not obvious from a quick review of the code itself.
 
 CSS 3
-=====
+*****
 
 CSS3 is used for styling and layout throughout the application. Extensive use is
 made of the Bootstrap Framework to aid in that process, however additional 
@@ -54,7 +54,7 @@ Styles should be specified clearly, one per line. For example:
 All stylesheets must be CSS3 compliant.
 
 HTML 5
-======
+******
 
 HTML 5 is used for page structure throughout the application, in most cases 
 being rendered from templates by the Jinja2 template engine in Flask. 
@@ -62,7 +62,7 @@ being rendered from templates by the Jinja2 template engine in Flask.
 All HTML must be HTML 5 compliant.
 
 Javascript
-==========
+**********
 
 Client-side code is written in Javascript using jQuery and various plugins.
 Whilst much of the code is rendered from static files, there is also code that
@@ -110,7 +110,7 @@ names.
      ES6 features and conventions.
 
 C++
----
+***
 
 C++ code is used in the desktop runtime for the application, primarily with the
 QT framework and an embedded Python interpreter. Note the use of hanging braces,
@@ -158,7 +158,7 @@ which may be omitted if on a single statement is present:
     }
 
 Python
-======
+******
 
 Python is used for the backend web server. All code must be compatible with 
 Python 2.7 and should include PyDoc comments whilst following the official