Fixed #23753 -- Added a suite of SQL Functions

Added functions and tests
Added docs and more tests
Added TextField converter to mysql backend
Aliased Value as V in example docs and tests
Removed unicode_compatible in example
Fixed console emulation in examples
Fixed #14180 -- Prevented unneeded index creation on MySQL-InnoDB

Thanks zimnyx for the report and Simon Charette, Tim Graham for
the reviews.
Forward-ported release note for 322560489
Fixed #24000 -- Corrected contrib.sites default site creation in a multiple database setup.
Fixed an inconsistency introduced in 547b1810.

mark_safe and mark_for_escaping should have been kept similar.

On Python 2 this change has no effect. On Python 3 it fixes the use case
shown in the regression test for mark_for_escaping, which used to raise
a TypeError. The regression test for mark_safe is just for completeness.
Fixed #23831 -- Supported strings escaped by third-party libs in Django.

Refs #7261 -- Made strings escaped by Django usable in third-party libs.

The changes in mark_safe and mark_for_escaping are straightforward. The
more tricky part is to handle correctly objects that implement __html__.

Historically escape() has escaped SafeData. Even if that doesn't seem a
good behavior, changing it would create security concerns. Therefore
support for __html__() was only added to conditional_escape() where this
concern doesn't exist.

Then using conditional_escape() instead of escape() in the Django
template engine makes it understand data escaped by other libraries.

Template filter |escape accounts for __html__() when it's available.
|force_escape forces the use of Django's HTML escaping implementation.

Here's why the change in render_value_in_context() is safe. Before Django
1.7 conditional_escape() was implemented as follows:

    if isinstance(text, SafeData):
        return text
    else:
        return escape(text)

render_value_in_context() never called escape() on SafeData. Therefore
replacing escape() with conditional_escape() doesn't change the
autoescaping logic as it was originally intended.

This change should be backported to Django 1.7 because it corrects a
feature added in Django 1.7.

Thanks mitsuhiko for the report.
Added release notes for the last two commits.
Fixed #24057 -- Fixed typo in docs/howto/custom-lookups.txt.
Fixed #24056 -- Fixed syntax highlighting in topics/testing/tools.txt.