GetFixedFrame transforms more frames than it needs to

[Amarcolina]

The current implementation of LeapProvider.GetFixedFrame calls GetTransformedFrame every time it obtains a new frame inside the inner loop. All but one of these frames is going to be discarded, and so the transformation is wasteful. It should acquire un-transformed frame objects, and only transform the once that is selected.

[cherullo]

This was also solved in PR #16.
By the way, regarding @protodeep 's commit above, it doesn't actually avoid multiple transformations, since the assignment to closest can happen more than once.
The leapMat assignment can also be taken out of the loop, since it's not supposed to change each iteration.
Also, isn't leap_controller_.Frame() == leap_controller_.Frame(0) ? If that's so, then shouldn't the loop begin with searchHistoryIndex = 1 ?

[codemercenary]

Tracking research is actually interested in building an extrapolation mechanism into the API which puts the extrapolation/interpolation responsibility on the API side. This would allow us to feed a timestamp down in to LeapC and retrieve an interpolated frame corresponding to that timestamp.

We should find a solution here which enables us to swap out the way the interpolation works at a later time, once it's supported by the underlying system.