introduced HtmlFormat.format
introduced ListWrapNodeFormatter and EnumWrapNodeFormatter in HtmlFormat
implemented an additional feature for HtmlFormat that allow to assign ids to headings
add an assertion for the test test_assign_id. bug #1: you should not touch the original tree
introduced BlockNode#node_id and methods that assign values of the id
abandoned the change introduced by commit 9d2b6ce. It was a wrong approach that alters visited trees
introduced BlockLeaf#node_id
fixed a bug that wrongly assigns NestedBlockLeaf#node_id
introduced HtmlFormat::HeadingNodeFormatter
reimplemented the additional feature for HtmlFormat that allow to assign ids to headings
add a test for ListWrapNode in TC_HtmlFormat
replaced ListWrapNodeFormatter and EnumWwrapNodeFormatter with ListLeafNodeFormatter
defined HtmlFormat::HeadingNodeFormatter#make_html_element to assign the name of its heading element as a value of class attribute
introduced HtmlElement#configure
use HtmlElement#configure to tidy up HeadingNodeFormatter, HeadingLeafFormatter and ListLeafNodeFormatter
in HtmlElement: make style elements rendered properly