happyR v2.0

Merge key functionality from happyCompare:

• Load multiple hap.py results from a samplesheet
• Helper functions to calculate credible intervals from extended metrics
• New vignettes for loading data and analysis of stratified counts

Public happyR release

• Load hap.py results with read_happy
  • Large files are lazy-loaded
• Support for combining (c) and extracting (extract_results) multiple inputs
• Getters for Precision-Recall datasets (pr_data)
• pkgdown docs and Precision-Recall vignette