plot.dsobs: Plotting functions for observations of dive trajectories
In jmhewitt/dsdive: Discrete Space Models for Dive Trajectories of Animals

Builds a ggplot2 graph.

## S3 method for class 'dsobs'
plot(
  x,
  depth.bins,
  stages = NULL,
  errorbars = FALSE,
  underlay = NULL,
  imputed.alpha = 0.3,
  imputed.list = NULL,
  time.as.POSIXct = FALSE,
  ...
)

`x`	`dsobs` object with record of observed depth bins
`depth.bins`	n x 2 Matrix that defines the depth bins. The first column defines the depth at the center of each depth bin, and the second column defines the half-width of each bin.
`stages`	Optional vector of for which dive stage the trajectory was in at each observation
`errorbars`	If `TRUE`, then the minimum and maximum depth for each bin will be included in the plot.
`underlay`	additional `ggplot2` layers to place before the main plot layers
`imputed.alpha`	transparency value used for plotting imputed trajectories, if provided
`imputed.list`	A `list` of `dsdive` objects to be plotted underneath the main `dsdive` trajectory `x`. The intent is that `imputed.list` will contain imputed trajectories.
`time.as.POSIXct`	if `TRUE`, will convert plotting times to POSIXct
`...`	(currently unused) additional plotting parameters

data('dive.sim')
attach(dive.sim)

# basic plot
pl = plot(x = sim.obs, depth.bins = depth.bins)

# plot with stages overlaid
pl2 = plot(x = sim.obs, depth.bins = depth.bins, stages = sim.obs$stages)

# plot with trajectory underlaid
pl3 = plot(x = sim.obs, depth.bins = depth.bins, imputed.list = sim)

detach(dive.sim)