[book] fix docstrings to please sphinx example rst roles in docstring must be protected (in a literal).

[book] several fixes in the rst files - prevent duplicate markup definitions, - use existing Workflow markup instead of redefining one (in baseschema.rst) - include dataimport - fix non-existant directive autodocfunction - remove the empty 'embedding.rst' file

[book] activate the viewcode extension Automagically make link to class/modules/etc. it finds in the documents.

[book] new theme based on pyramid theme (closes #4291287)