brokenstick 2.4.0

Major changes:

Major update to Broken Stick Model for Irregular Longitudinal Data to sync with revision JSS manuscript version dated 30-10-2022.
Hiding knots is convenient and automatic by setting the hide entry in the brokenstick object. The hide argument can also be used in print(), plot(), get_knots(), get_omega() and summary().
Changes the default number of knots in brokenstick() to 5. The former default produced a solution without internal knots. The new default produces a generally more informative starting model when the user does not specify knots (using knots = c(..., ...)) or the number of knots (using k = ...).
Replaces the strip_data argument in predict() by the a more intuitive include_data argument. By default, observed data are now included into the predictions, similar to predict.lm().
Turns error Argument 'newdata' is required for a light brokenstick object. of brokenstick() into a warning and returns NULL.
Adds new cor and lower arguments to summary.brokenstick() to tweak output.
Adds documentation for S3 output functions.
Adds an example to plot.brokenstick() on how to create a black and white figure of trajectories

Adds hide field to brokenstick object
Adds hide arguments to coef.brokenstick(), summary.brokenstick(), plot(), get_knots() and get_omega
Replaces what argument of get_omega() by cor
Separates summary() and print() functionality
Updates smocc_200 and fit_200 objects
Updates to roxygen 7.2.1
Replace hard-coded variable name hgt_z by a dynamic name (#8)
Extends capabilities of plot_trajectory() with shape and linetype options
Replaces knots = 0:3 by knots = 0:2 in examples
Updates the perfectmodel vignette
Expression predict(fit_200_light, x = "knots") now produces warning message instead of crashing
Updates objects fit_200 and fit_200_light to use automatic boundary (2.68y) instead of 3 yrs
Automatically sorts any user-specified values for knots in increasing order to evade problems with predict()