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When loading a canvas from previous versions, set the split_angle and the split_radius to have the same value than split, in order to keep the functionality.
When tangent1, tangent2 or split_tangent_angle or split_tangent_radius are modified, then update the tangent2 accordingly. Deprecate split_tangent in favor of the combination of both split flags.
When filling a BLinePoint the order is important, since the tangent2 is now updated when the flags are set. Fill first the flags and second the tangents