Changes to the `trajr` package

trajr 1.4.0

Allow the creation of trajectories with 0 points in TrajFromCoords.
Fixed bug in TrajSpeedIntervals: no intervals were being returned if the entire trajectory qualified as an interval.
Fix bug in plot.TrajSpeedIntervals: time (x-axis) didn’t handle trajectories with a non-zero starting time.
Added functions to assist in simulating trajectories that are bounded or vary spatially in some way. The new functions are TrajInPolygon, TrajSplit, TrajMerge and TrajSplitAtFirstCrossing.
Added functions to calculate velocity and acceleration: TrajVelocity and TrajAcceleration. The documentation for TrajDerivatives has been updated to state that the acceleration returned is not really acceleration, rather it is change in speed over time.
Added argument diff to TrajSpeedIntervals to control how speed is calculated. Default is “backward” so the function is backwards-compatible, although “central” is usually a better choice.

Detect and report some invalid parameter values.
Altered handling of parameter readcsvFn to TrajsBuild to make it possible to use readr::read_csv without a wrapper function.
Added function TrajResampleTime to resample a trajectory to fixed step times.
Added parameters start.pt.pch and start.pt.col to plotting functions.
Added parameter dt to TrajTranslate
Fix vertical extents of rectangles in plot.TrajSpeedIntervals to handle non-default ylim values.
Added optional progressbar to TrajsMergeStats.
TrajsMergeStats now passes the arguments stringsAsFactors = FALSE to rbind. This prevents incorrect behaviour and the warning “invalid factor level, NA generated” if one or more of your statistics are characters.
Enhanced TrajRotate to allow absolute rotation and arbitrary origin of rotation.

Added correct citation.
Fixed: plot.TrajSpeedIntervals was not passing additional arguments (...) to plot.
Added: functions TrajDuration, TrajMeanVelocity, TrajTranslate.
Added translateToOrigin parameter to function TrajsBuild.