TODO for version 1.0
- Think about what a user would expect from version 1.0
- Support model definitions without pathway to sink in combination with formation fractions
- Complete the main package vignette named mkin to include a method description
- Calculate pseudoDT50 values as recommended by FOCUS
- Improve formatting of differential equations in the summary

Nice to have:
- Calculate confidence intervals for DT50 and DT90 values when only one parameter is involved
- Calculate transformation only DT50 values (exclude pathways to sink) as additional information
- Calculate DT50 values from smaller rate constant/eigenvalue of DFOP, HS and SFORB models
- Check possibility to include a stripped extJS in gWidgetsWWW2, or to publish a separate
  R package for extJS