Section::TrimSection resulting in bad key values at start and end of trim range

The trim process inserts keys at the start or end of the range depending if you specify Trim Left or Right, I'm finding that Trim right is inserting a key at the end of the section that is incorrect.

Ie. my initial Section contains 2 keys, T=-70,V=0 and T=1314,V=1901

If I TrimLeft at Time 1173 I get a key inserted at T=1173 with a value of 1689.5, which is correct.

If I then TrimRight at Time 1226 I get a value inserted at 1226 with a value of 1738.03, this is wrong, value should be 1769.

Also All keys added by the trim command are set to Cubic(Auto) with there in out tangents being 0 (horizontal), so the resulting curve follows an S shape rather than the Linear path the original source curve follows.

Steps to Reproduce

• Create a level sequence
• Add a spawnable cube to the level sequence
• Animate the cube's Z position from 0 to 500 over the span of the sequence using linear keys
• Open the curve editor and look at the Z curve
• Move the sequencer play head to the middle of the sequence, right click on the transform section and select Split Section from the Edit menu.
• Open the curve editor again and look at the curves for the cube's transform

RESULT

The two sections' curves do not match the previous curve, and the newly added keyframe is cubic, not linear. If you repeat the repro with cubic keys, the resulting tangents from the newly added keys will be incorrect.

Expected

The keys added by splitting sections should behave like adding a key in the UI