remove unused code

[adokter]

• rename isFactor to is_divisor
• remove unused function

[codecov[bot]]

Codecov Report

Merging #625 (9050a1f) into master (4f5b129) will increase coverage by 0.13%. The diff coverage is 100.00%.

:exclamation: Current head 9050a1f differs from pull request most recent head 8a0362b. Consider uploading reports for the commit 8a0362b to get more accurate results

@@            Coverage Diff             @@
##           master     #625      +/-   ##
==========================================
+ Coverage   82.11%   82.25%   +0.13%     
==========================================
  Files          61       61              
  Lines        3702     3696       -6     
==========================================
  Hits         3040     3040              
+ Misses        662      656       -6     

Impacted Files	Coverage Δ
R/as.vpts.R	93.10% <100.00%> (ø)
R/utils.R	91.66% <100.00%> (+5.39%)	:arrow_up: