NumberStyle: do not automatically convert numbers with_html.

In some cases, we have numbers which are _already_ in the appropriate
style. Most notably, when considering the user input values from which we
made the style determinations in the first place.

This fixes the bug, but is still unsatisfying because we would need
to convert both in and out in order to do better input styling.
Conversions: moving triggers to "any"
Conversions: Fixing bug and simplifying parsing
Conversions: Switching to named matches
Conversions: Adding support for how many <units> in <quantity> of <other_units>?
Conversions: Adding failing tests for 'how many pounds in kilogram'
Conversions: naming more regex components
Conversions: supporting "how many <unit> in <unit>"
Conversions: Adding support for a and an in 'how many cm in an inch?' and 'how many cm in a metre?'
Merge remote-tracking branch 'origin/master' into mintsoft/conversions_questions

Conflicts:
	t/Conversions.t
Conversions.t: organize into sections.

As the breadth and depth have increased here, it can be difficult to know
where to add new regression tests.  Hopefully this makes it easier.

Also convert '-ANY-' for HTML checking to make it more clear that we are
intentionally not checking.
Conversions.pm: remove unused module.
Conversions: allow articles to imply 1 on source units.

Thanks to @mintsoft for making this so easy to accomplish!
Conversions: add set_unit_pluralisation.

No matter how we matched or what unit is set in Convert::Pluggable
try to get count unit match.
Conversions: try to useplural context to pick implicit 1.

We should not flip when the second unit is plural, since we can infer
the 1 on the other unit.  The "two plurals with not numbers" case is
now unflipped, but this was always ambiguous, so I don't think this is
worse than before.
Conversions: Adding tests around plurals in area and volumes
Conversions: moving triggers to "any"
Conversions: Fixing bug and simplifying parsing
Conversions: Switching to named matches
Conversions: Adding support for how many <units> in <quantity> of <other_units>?