Python API documentation generation tool Code

removed the "HTML postprocessing" required to fix excessive spacing.

- Added an ``inline`` attribute to `Ticket` and `Element`. Inline elements
are similar tho HTMl ``<span>``; they are rendered in HTML without ``<p>``.
Inline elements are, for instance:

- list items (fields too);
- docstring summaries;

- HTML code simplified: no more ``<br><br>`` to accomodate for the lack of
``<p>``. This layout is more CSS-friendly.

- Paragraphs vertical margins tweaked.

- H3 top margin value set for cross browser consistency (IE and FF have
different defaults).