Carry out multiple runs of an MP for a given dataset over a grid of values
for the MP/HCR paramaters, in order to find the parameter combination(s) that
give the best performance over the chosen statistics, a.k.a. *tuning*

`tune(mp, grid, statistics, refpts, ...)`

## Arguments

- mp
A function executing a projection applying a given MP, see `mseBasic`

for an example

- grid
A name list of *mp* argument values to loop along

- statistics
A list of performance statistics

- refpts
The reference points needed to compute the statistics, *FLPar*

- ...
Any other arguments to be passed on to *mp*

## Value

A list or aggregatecd FLR object, depending on the output of *mp*