core: Continue PieCrust3 refactor, simplify pages. The asset pipeline is still the only function pipeline at this point. * No more `QualifiedPage`, and several other pieces of code deleted. * Data providers are simpler and more focused. For instance, the page iterator doesn't try to support other types of items. * Route parameters are proper known source metadata to remove the confusion between the two. * Make the baker and pipeline more correctly manage records and record histories. * Add support for record collapsing and deleting stale outputs in the asset pipeline.

import shlex
from piecrust.publishing.base import ShellCommandPublisherBase


class ShellCommandPublisher(ShellCommandPublisherBase):
    PUBLISHER_NAME = 'shell'

    def _getCommandArgs(self, ctx):
        target_cmd = self.getConfigValue('command')
        if not target_cmd:
            raise Exception("No command specified for publish target: %s" %
                            self.target)
        args = shlex.split(target_cmd)
        return args