- revised the transformation building logic.
- rectified to properly search "this" composition layers.
- rectified the linear interpolation implementation.
- added "pingpong" looping attributes.
The current development of the expression engine is experimental.
It does not support multi-threading.
Therefore, when tvg::Initializer::init() is configured
with more than one thread, expressions will be automatically disabled.
issue: https://github.com/thorvg/thorvg/issues/1640