v0.18.0

• allow to save perturbation-schemes for different variables in params_cnts_set() and params_nums_set()
• allow return current active perturbation parameters for variables with params_cnts_get() and params_nums_get()
• added new convenience methods allvars(), numvars() and cntvars() returning variable names eligable for perturbation
• implemented the perturbation of numerical variables
  • new method ck_params_nums() to define perturbation parameters for continuous variables along with helper-functions ck_flexparams() and ck_simpleparams()
  • new method numtab() to extract numerical tables
  • new method mod_nums() returning modifications for numerical variables
• updated methods print() and summary() to include information about perturbed continuous variables
• new methods reset_cntvars(), reset_numvars() and reset_allvars() to remove perturbation results and provided perturbation parameters
• new methods to identify sensitive cells
  • $supp_freq(v, max_n)
  • $supp_nk(v, max_n)
  • $supp_p(v, max_n)
  • $supp_pq(v, max_n)
• added test-cases and improved coverage
• make use of ptables from ptable-pkg
• Reproducibility:
  • allow to write perturbation parameters as yaml in ck_params_nums() and ck_params_cnts()
  • allow to import such parameters with ck_read_yaml()
• updated and extended package vignette