New effect sizes, ES aggregation, and replication code

This is major release that includes new effect size calculation functions, new post-processing features, and updates to the built-in shiny app. Changes were as follows:

• batch_calc_ES() gains an argument aggregate, for post-processing effect size estimates by averaging across the levels of a variable.
• Added functions for calculating two new effect sizes:
  • log ratio of medians
  • baseline-corrected Tau
• Updates to SCD_effect_sizes() shiny app.
  • Added aggregate feature.
  • Added log ratio of medians and baseline-corrected Tau effect size measures.
  • Allowed use of .xlsx files.
  • R code for replicating the batch calculation.