To do 
high priority
- allow for dose finding with active control

lower priority
- bootstrap methods for precision of the target dose
- allow for different maxEffs (and baselines)
  for planning
- allow for different clinical relevance thresholds for
  analysis
- add covMu argument for planning functions
- Function to evaluate power and precision of the dose
  estimate (under a certain dose design) by simulation
- Function to interactively choose guesstimates
- verbose argument for print.summary.MCPMod?

