Merge remote branch 'enthoughtbase/master'
FIX: Replace imports to .api to avoid possible circular imports

The module was previously importing from `.api` which was causing
a circular import when the user would import directly `traits.adapter`.
ENH: Add an "allow_selection" option to the Title trait and TitleEditor.
ENH: Added ui_dispatch() which will call a handler immediately if it is already in the main thread, but move it to the main thread otherwise.
BUG: Fixed behavious of .update() on copied TraitDictObjects
Merge branch 'master' of github.com:enthought/traits
DOC: minor corrections
DOC: Create/Add api_reference documentation
Add :noindex: role to avoid index conflict
reduce the doctree depth
update RefactorDoc to the latest version
add autsosummary and default flags for autodoc
DOC: Separate classes, functions, ... in documentation
Remove uneccessary currentmodule directive
Copy comments to the docstrings
Convert comments to autodoc friendly ( # -> #: )
Copy comment to docstring.
Copy comment to docstring
Make comments to autodoc friendly ( # -> #: )
DOC: # -> #: