====Aligner markup====

An aligner is a special single-line token which specifies the alignment of the subsequent text. It is essentially
'modal' - all text from the token onward (until another aligner is encountered) is wrapped in a ''%%<tw-align>%%'' element
(or unwrapped in the case of left-alignment, as that is the default).

  * Right-alignment, resembling ''%%==>%%'' is produced with 2 or more ''%%=%%''s followed by a ''%%>%%''.
  * Left-alignment, resembling ''%%<==%%'' is restored with a ''%%<%%'' followed by 2 or more ''%%=%%''.
  * Justified alignment, resembling ''%%<==>%%'' is produced with ''%%<%%'', 2 or more ''%%=%%'', and a closing ''%%>%%''.
  * Mixed alignment is 1 or more ''%%=%%'', then ''%%><%%'', then 1 or more ''%%=%%''. The ratio of quantity of left ''%%=%%''s and right ''%%=%%''s determines
the alignment: for instance, one ''%%=%%'' to the left and three ''%%=%%''s to the right produces 25% left alignment.

Any amount of [[harlowe:whitespace|whitespace]] is permitted before or after each token, as long as it is on a single line.

=== Example usage: ===

<code>
==>
This is right-aligned
  =><=
This is centered
 <==>
This is justified
<==
This is left-aligned (undoes the above)
===><=
This has margins 3/4 left, 1/4 right
  =><=====
This has margins 1/6 left, 5/6 right.
</code>