added possibility to shrink ratios using Rgbp or normal model
added method 'ttest2' for quantification
Merge branch 'master' of github.com:fbreitwieser/isobar

Conflicts:
	inst/report/properties.R
fixed various NOTEs and use of global variables
removed shrinkage functions (kept in branch shrink-ratios until fully tested)
cleared documentation errors
minor fixes