Adding Best Estimate Index methodology

See merge request !29

Remove manual pdf introduce in develop-ens-biascorrection

See merge request external/cstools!36

Develop ens biascorrection

See merge request !15

Fix in the documentation to include a metion to S2S4E project

See merge request external/cstools!35

Functions to transform formats to s2dv_cube() and as.s2dv_cube()

See merge request external/cstools!28

Removing aperm manipulations before the Apply function in CST_Calibration.R and partly reversing corrections of Verónica.

Merge branch 'develop-ens-biascorrection' of http://earth.bsc.es/gitlab/external/cstools into develop-ens-biascorrection

Suggestions of Verònica implemented. More specifically: 1) implementation of multiApply as wrapper, 2) removal of ... 3) warning when multi.model is used, 4) adaptation of the manual by addition of bias method, discussion of use of multi.model boolean, change of adequate reference to 2011 paper for evmos method.