1D parameter scan functionality

[kratsg]

Description

if the likelihood becomes more complicated and you want to visualize the maximum likelihood (with respect to all but one parameter) as a function of that one parameter

Something akin to the documentation shown here would be nice to include: https://myfitter.hepforge.org/doc-1.1/profile.html

Ideally, we need to make this interface somewhat easier or at least describe in documentation how one does it.

[kratsg]

Story:

convert a simple model (one signal, one background, one background uncertainty and a signal strength parameter) from xml and get best fit point plus parameter uncertainties, and compare that to a ROOT implementation

[lukasheinrich]

this will be trivial once we have batch support .