Topic/plat 6640 part1

This is part 1 of the PR for the refactored caplet stripping code. This involves removing of old code and the adding of an interface (CapletStripper) and classes to handle the results of the strippers, but no actual concrete functionally on the calibration side.  
I'm not asking for this to be changed as part of this PR as it's only a private method, but I'll remark that it's a bit of a misleading method name - its true purpose really seems to be to get the fit parameters from a `LeastSquareResults` - this makes the call to `super()` above look like it's passing in a `LeastSquareResults` rather than a `DoubleMatrix1D` if you take the name `check` at face value.