Dev-QC: slice off first frame of encoder wheel plots

[arielleleon]

The first frame of the mouse speed plots should be chopped off. Because the first value can be high, it can throw off the y-axis scaling making it hard to read

[macarenasa]

Instead of slicing off first frame of wheel encoder plots - mark where calculation begins on plot to maintain data integrity.

• limits on y-axis - box to outline data not included in calculation.

[DowntonCrabby]

also add a horizontal line to the plots to indicate the <100cm per sec wheel artifact threshold

[samiamseid]

completed as part of this duplicate #287

Can confirm horizontal line is present