vector: Performance improvements in expressions
Read values from the tiles directly into a ShumateVectorValue rather than going through GValue, which is slow. Also added shumate_vector_value_steal(), which lets us skip some strdup()s.
Read values from the tiles directly into a ShumateVectorValue rather than going through GValue, which is slow. Also added shumate_vector_value_steal(), which lets us skip some strdup()s.