interpolateTrack: Interpolate Track Positions
In jtextor/MotilityLab: Quantitative Analysis of Motion

Approximates the track positions at given time points using linear interpolation (via the approx function).

1	interpolateTrack(x, t, how = "linear")

`x`	the input track (a matrix or data frame).
`t`	the times at which to approximate track positions. These must lie within the interval spanned by the track timepoints.
`how`	specifies how to perform the interpolation. Possible values are `"linear"` (which uses `approx` with default values) and `"spline"` (which uses `spline` with default values).

## Compare interpolated and non-interpolated versions of a track
bb <- boundingBox( TCells[2] )
plot( TCells[2] )
t2i <- interpolateTrack(TCells[[2]], seq(bb[1,"t"],bb[2,"t"],length.out=100),"spline")
plot( tracks( t2i ), add=TRUE, col=2 )