Blender Git Loki

Support for an optional semantics argument when interpolating cached
properties.

This is necessary to distinguish e.g. vector semantics (linear vs. slerp
interpolation for positional/normal vectors). It would be simpler to
do this based purely on types, but the typing of common Alembic
properties is not sufficiently unique. Semantics arguments are enum
values, that can be omitted if the default interpolation should be used.