Improve QC and exploration

[TuomasBorman]

Current version of QC and exploration chapter is rather unstructured and just shows available methods. I think the chapter would greatly benefit more structured approach. For instance, the paper below could be cited

Zuur, A.F., Ieno, E.N. and Elphick, C.S. (2010), A protocol for data exploration to avoid common statistical problems. Methods in Ecology and Evolution, 1: 3-14. https://doi.org/10.1111/j.2041-210X.2009.00001.x