[SPR-4702] now updating TestContext state before calling before/after test class life cycle callbacks.

* eliminated all usage of "the section entitled", because <xref> links already render including "the section called ".  This was resulting in sentences like 'see also the section entitled the section called "@Autowired"'. This issue affected nearly all sections of the documentation, so went beyond just beans.xml

* fixed table overflow in the "Using filters to customize scanning" section (approx. p.90)

* fixed all code overflows in <programlisting/> elements

* corrected a couple minor syntax errors with SpEL examples (missing closing braces)

* added 'language="..."' element to <programlisting> elements where appropriate to enable syntax highlighting.

* normalized all code indention to four-space (some code listings were using one- and two-space)

* updated all code listings to use same-line opening braces.

* eliminated section regarding backward compatibility with Spring DTDs and singleton=true|false.  This seems like cruft to me, and we shouldn't keep historical notes around forever.

* Added <note> regarding the new thread scope (SimpleThreadScope) to Section 3.5 Bean Scopes.  Also updated the section on registering a custom Scope implementation to use the SimpleThreadScope as an example.

* updated the new-in-3.xml section to improve the @Configuration example