* Improve how the extend lines collision is calculated.
* Added `S` key to switch between modes.
* Now extend factor does not disable visual aids (thi sis done with checkbox).
* Reduce the use of linked list and now memory array is used.
* Refactor Radius functions.
* Fixed bug of Radius mode when object is rotated.
* Cleanup code.
Differential Revision: https://developer.blender.org/D16022