1. markup for definition lists is now supported, if enabled
    during configuration with the `--with-dl-tag` option.
    The new markup is ^=tag=$, with the list item -- indented
    at least 4 spaces -- beginning on the very next line.
 2. start writing public interfaces to get at some of the
    internals in the code.
 2. a sample ``mkd2html'' program that demonstrates the
    (still unfinished) internal interfaces.
 3. correct the order of `<code>` and `<pre>` in code blocks.
 4. properly inherit from the parent frame in `reparse()`
 5. add a parse tree dumper (`dumptree()`) and modify the
    `markdown` program to use it when passed the **`-d`**
    flag.
 6. Rip `markdown.c` in half; one half is the backend html
    generator, the other half is the tree builder.
 7. change `mkd_text()` and `markdown()` to return `int`
 8. write a manpage for `markdown(1)`.
 9. completely rework the way whitespace is handled.  It is
    now a paragraph *separator*, not a terminator.
10. configuration cleanups to make it happier on more platforms.