Enable the option of having a linear combination of representative days for the ORDO method

[datejada]

Enable an option to have the Optimal Representative Days Orderer (ORDO) using a linear combination of representative periods.

• [ ] It needs changes in the function representative_periods_ordering to accept a new parameter
• [ ] Double-check the cosine distance (from the medoidal cones approach) performance versus the current objective function (euclidean distance type)
• [ ] Changes in SpineOpt to accept the parameter exp_weight depending on all the representative periods.
• [ ] Add new Tests