SIP currently has explicit support for PyQt hard-coded via the undocumented %Plugin directive. This will be replaced by a general purpose extension mechanism and the PyQt-specific support will be moved to PyQt-builder using that mechanism.

This mechanism will only be supported for the new ABI v14 to be implemented as part of the support for PEP 489 (see issue #34). This minimises the changes (and therefore the risk of regressions) to the current v12 and v13 ABIs.