gsDesign2 1.0.0

The version

• merges the gsDesign2 v0.2.1 and gsdmvn;
• supports organized summary tables and gt tables;
• has power/sample size calculation for risk difference;
• has functionality for integer sample size;
• updates API (see the 1:1 map between the old API vs. new API in #84);
• fixes historical small bugs like
  • expected_accrual for the stratified population;
  • gs_spending_bound when IA is close to FA;
  • gs_power_bound when applied in the max combo test;
  • gs_design_npe for type I error;
  • ...
• develops fixed_design to implement different methods for power/sample size calculation;
• adds info_scale arguments to gs_design_xxx and gs_power_xxx;
• adds RMST and milstone methods into fixed design;
• adds and re-organizes vignettes.