Documentation: Multiple changes to doc format

- Removed "Files" node from the left panel and allows to customize the
contents of the left panel by editing DoxygenLayout.xml.
- ARIMA: Reformated syntax to one arg per line and add results to
 example.
- Other modules:
    - Syntax arguments one per line, changed presentation of defaults
    - Revised menus, syntax, arguments, examples for consistency.
    - Corrected misspelling and other typos