the first commit for MarkDownFormat
added <strong> and <em>
defined ListWrapNodeFormatter#visit()
defined EnumWrapNodeFormatter#visit()
refactoring of ListWrapNodeFormatter#visit()
refactoring of HeadingNodeFormatter#visit()
defined QuoteNodeFormatter#visit()
supported the verbatim block in GFM style
supported GFM style strikethrough
supported horizontal rules
refactoring of EmNodeFormatter and StrongNodeFormatter
defined TableNodeFormatter#visit()
defined TableNodeFormatter#calculate_cell_width()
The width of a coverted table is now properly calculated
_ and * in the source text in Hiki notation are now escaped
cosmetic changes
insert a new line after headings
defined CommentOutLeafFormatter#visit()
a verbatim block should be surrounded by blank lines
add a blank line after each paragraph