Add necessary path settings for tests in top-level tests/ directory
Add necessary path settings to use pocompile for test_mo.py
Skip search/indexing tests if no indexers are available
Skip these tests if we don't have iniparse
Skip if we don't have aeidon
Skip if we can't load cpo because "gettext PO library not found"
Escape &x0022 -> "

A non-roundtrip one
Decode » in DTD

Convert text to Unicode earlier so we can do the conversion correctly.
Install additional Mozilla related tools
Document Translate Toolkit use of pytest and plugins
Revise pytest docs with code-block & cross-refs

add pytest to intersphinx links in conf.py
refactoring comma etcetera
update pytest version dependency & recommendation
add (non-inline) hyperlink to pytest.org
one combined code-block:: bash for all command-line examples
eliminate Plugins section: importorskip() and deprecated_function() are builtin
rewrite skipping text to reflect above, drop hyperlink for :ref:/:func: below
add subsubsections for each function and decorator
add intersphinx :func: cross-reference for importorskip()
code-block:: python for all examples
use :ref: for skipif - expands to subsection title, so reworded to match
note decorators on classes require Python 2.6
use :ref: for xfail - expands to subsection title, so reworded to match
expand explanation of xfail decorator parameters, fix bug in simple example
intersphinx :func: for deprecated_call(); as it's builtin, now before recwarn
italicized hyperlink to recwarn as it lacks defined :ref: target
Better use of intersphinx :ref:, less passive voice
Document the use of code-block's
Fix some docstring formatting
Drop indent
Switch between highlighters
Changes in PHP format docs