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 * They also support deleting output files that are no longer valid.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.

@echo off
setlocal

set CUR_DIR=%~dp0
set CHEF=%CUR_DIR%..\bin\chef
set OUT_DIR=%CUR_DIR%..\piecrust\res\messages
set ROOT_DIR=%CUR_DIR%messages

%CHEF% --root=%ROOT_DIR% bake -o %OUT_DIR%
del %OUT_DIR%\index.html