These notes should have been in the previous commit message. Added `task_list` extension. API changes: + Added constructor `Ext_task_lists` to `Extension`. + Added `taskListItemFromAscii` and `taskListItemToAscii` to Text.Pandoc.Shared. Task lists are supported form markdown and gfm input. They should work, to some degree, in all output formats, though in most formats you'll get an ordered list with a following task list box. In HTML and LaTeX/PDF output, the bullet will be suppressed for nicer output.