core: Start of the big refactor for PieCrust 3.0. * Everything is a `ContentSource`, including assets directories. * Most content sources are subclasses of the base file-system source. * A source is processed by a "pipeline", and there are 2 built-in pipelines, one for assets and one for pages. The asset pipeline is vaguely functional, but the page pipeline is completely broken right now. * Rewrite the baking process as just running appropriate pipelines on each content item. This should allow for better parallelization.

include CHANGELOG.rst
include INSTALL.rst
include LICENSE.rst
include README.rst

include pytest.ini
include setup.cfg
include requirements.txt
include dev-requirements.txt

recursive-include piecrust *
recursive-include tests *

global-exclude *.py[cdo] __pycache__ *.so
global-exclude .DS_Store Thumbs.db Desktop.ini
global-exclude *.swp *~ *.bak