Better error management and removal support in baking/processing. * Baker and processor pipeline now store errors in their records. * They also support deleting output files that are no longer valid. * The basic transitional record class implements more boilerplate code. * The processor pipeline is run from the `bake` command directly. * New unit tests. * Unit test mocking now mocks `os.remove` too.

class TemplateNotFoundError(Exception):
    pass


class TemplateEngine(object):
    EXTENSIONS = []

    def initialize(self, app):
        self.app = app

    def renderString(self, txt, data, filename=None, line_offset=0):
        raise NotImplementedError()

    def renderFile(self, paths, data):
        raise NotImplementedError()