Make possible to build tmpl-spec bundle containing all project templates

When coverage is enabled a special bundle (_coverageBundle by default) will be built. It will be made of all the template files from the build levels. It will not contain any tests. This makes the coverage report to contain statistics about all project templates, but not just ones that were used by the tests.
`vfs.makeDir` можно перенести в `vow.all` ниже, чтобы не портить переменную