This version uses just turn angles and step lengths to define the correlated random walk.

```
move(hypothesis = "crw", ...)
crw(agent, extent, stepLength, stddev, lonlat, torus = FALSE)
"crw"(agent, extent, stepLength, stddev, lonlat, torus = FALSE)
"crw"(agent, extent, stepLength, stddev, lonlat, torus = FALSE)
```

hypothesis

Character vector, length one, indicating which movement
hypothesis/method to test/use. Currently defaults to
'crw' (correlated random walk) using

`crw`

....

arguments passed to the function in

`hypothesis`

agent

A

`SpatialPoints*`

object.
If a `SpatialPointsDataFrame`

, 2 of the columns must
be `x1`

and `y1`

, indicating the previous location.
If a `SpatialPoints`

object, then `x1`

and
`y1`

will be assigned randomly.extent

An optional

`Extent`

object that will be used for `torus`

.stepLength

Numeric vector of length 1 or number of agents describing
step length.

stddev

Numeric vector of length 1 or number of agents describing
standard deviation of wrapped normal turn angles.

lonlat

Logical. If

`TRUE`

, coordinates should be in degrees.
If `FALSE`

coordinates represent planar ('Euclidean')
space (e.g. units of meters)torus

Logical. Should the crw movement be wrapped to the opposite
side of the map, as determined by the

`extent`

argument.
Default `FALSE`

.-
A SpatialPointsDataFrame object with updated spatial position defined by a
single occurence of step length(s) and turn angle(s).

McIntire, E. J. B., C. B. Schultz, and E. E. Crone. 2007. Designing a network for butterfly habitat restoration: where individuals, populations and landscapes interact. Journal of Applied Ecology 44:725-736.

`pointDistance`