checkapidoc: deal with the two cases of `__init__.py` files
checkapidoc: deal with the two cases of `__init__.py` files

 - if only the module itself is documented (e.g. `trac_mimeview`) and no 
   .rst files for submodules are present, we include the re-exported symbols
   as well (this was the behavior so far for `__init__.py` files)
 - when submodules are also documented (e.g. `trac_util.rst` and the various
   `trac_util_*.rst` files), we only consider the symbols defined in
   `__init__.py`, as for a normal module


git-svn-id: 0d96b0c1a6983ccc08b3732614f4d6bfcf9cbb42@11274 af82e41b-90c4-0310-8c96-b1721e28e2e2

rbaumg/trac,rbaumg/trac,rbaumg/trac,rbaumg/trac