Fix bug that meant non-linear path factors weren't stored in output of
splatSimulatePaths

* Add locfit to NAMESPACE
* Add return values to logistic, showPP documentation
* Delete commented mergeParams function
* Switch to aes_string in compareSCESets
* Add examples to getParam, setParam
* Adjust line lengths
* Adjust indentation

Getting note about scDatEx, but think it should be fine...

estimateSimpleParams -> simpleEstimate
estimateSplatParams -> splatEstimate

Neater than having a checkValid option

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

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