Make it clearer what is new and old

* lun:
  Run checks
  Fix doc links to other packages
  Document simLun
  Add DE to simLun
  Add addition Lun params to splatParams
  Add basic simLun function

* simple:
  Add tests for simple simulation
  Rename splat sub functions to differentiate
  Add simSimple function

The splat sub function names were in the same format as the simulation names.
Changed to make it obvious they are different.

* simulate: (22 commits)
  Test that splat output is a valid SCESet
  Add single mode to splat
  Allow different DE parameters for each group/path
  Add progress messages
  Add seed paramater and seed simulation
  Rename n.genes, n.cells, n.groups for consistency
  Modify outlier expression to use median
  Run checks
  Add simulation documentation
  Add simPathCellMeans function
  Add expandPathParms function
  Add simPathDE function
  Add extra checks checkParams
  Fix bug in mergeParams
  Add simDropout function
  Add simTrueCount function
  Add simBCVMeans function
  Add simGroupCellMeans function
  Add simulateLibSizes function
  Add simulateDE function
  ...

Should make sure they are actual outliers and better matches the estimation
method.

Rename old function to include group

Check that path.from has possible values

Check if any is.na to avoid warning