Consider body pinned frame representation for dynamics algorithms

[jslee02]

DART use body fixed frame representation for dynamics algorithms since it is faster according to Featherstone's study. Through some accuracy test, however, we discovered that there are some cases that body fixed frame representation is less accurate than body pinned frame representation. Body pinned frame is a frame that the position is at the origin of the body fixed frame and the orientation is aligned to the world frame's (so the orientation part is just identity).

We need to figure out the exact computational cost of body pinned frame representation first, and then make a choice whether we switch to body pinned frame representation.

[stale]

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