chasmani/piecewise-regression: v1.5.0

Changes:

• Modified the Davies test for the existence of one breakpoint to use the Wald test as a test statistic, following Muggeo, V. M. (2008). Segmented: an R package to fit regression models with broken-line relationships. R news, 8(1), 20-25.
• Added tests for the Davies test with a range of data models.
• Added the option to get model fit parameters easily with a convenience function get_params on the Fit object.
• Added the option to get data predictions easily with a convenience function predict on the Fit object.
• Made small changes in response to issues raised.