- Fix analytical and Eivenvalue based solutions after transition to fitting
  transformed k and f values
- Transfer calculation of DT50 and DT90 calculations from mkinfit to summary.mkinfit
- Calculate back-transformed parameters in summary.mkinfit
- Report back-transformed parameters in print.summary.mkinfit
- Use back-transformed parameters for DT50 and DT90 calculations
- Calculate confidence intervals for parameters assuming normal distribution
- Calculate confidence intervals for DT50 and DT90 values when only one parameter is involved
- Fix DT50 and DT90 calculation for SFORB_SFO
- Add unit tests for mkinfit
- Remove dependency to kinfit
- Document validation against fits documented in chapter 13 of FOCUS (2006)
- Reproduce example anaylses (L1, L2, ...) in FOCUS (2006)
- Generate confidence intervals for DT50 and DT90 values for other cases