* efficiency improvements in r package
* add drop = FALSE to df subsetting
* adding two more drop = FALSE
* add back in global var vector
* revert to previous style of piecewise_linear, piecewise_logistic
* more reversion
* even more reversion
* revert get_changepoint_matrix
* trying to pinpoint issues
* more debugginh
* tests finally pass
* last commit of pr
* last commit of pr
* add utils to imports