The following changes are included:
- Added support for GPC data type.
- Added eager import of ``rattail.sil`` in ``before_render`` hook.
- Removed ``rattail.pyramid.util`` module.
- Added initial batch support: views, templates, creation from Product grid.
- Added batch params template for ``PrintLabels`` provider.
- Added support for ``rattail.LabelProfile`` class.
- Improved Product grid to include filter/sort on Vendor.
