- Reorganize top-level 'doc' Makefile target so submodules can easily
add their own doc-generating routines to it. e.g. the Bro project
makes a placeholder 'doc' target, then adds 'restdoc', 'sphinxdoc';
later Broccoli can add it's own target as a dependency for generating
API docs.
- Fixed generated docs for BIFs not being organized under a base/
subdirectory like the original source files.
- Fixed documentation style for function parameters not applying to
functions declared as record fields.
- Misc. script documentation tweaks to address warnings given by Sphinx.
