Introducing an ADVANCED snow_redistribution mode

Introducing an advanced snow_redistribution scheme, that uses the redepositSnow function to redistribute snow from the windward (luv) to the lee slope. This new redistribution mode is called 'ADVANCED', while the previous redistribution mode is still available as 'SIMPLE'. Using the old setting 'TRUE' prompts a warning and activates the SIMPLE mode.

Whereas the old SIMPLE mode took the eroded snow, and deposited this at the lee slope with the same density, the new ADVANCED mode uses the redepositSnow function, and hence modifies the density according to the selected DENSITY_REDEPOSIT, which in most cases is dependent on the wind speed. This leads to better representation of wind slabs.

This PR also includes modified formulation of the complex cluster of bools and if-statements in compSnowDrift. It is now structured by station type (main or virtual slope), and within those classes, checks for all conditions that determine erosion. It should function exactly as before, but be easier to comprehend. Specifically for the cases SNOW_EROSION=HS_DRIVEN and alpine3D, it would be good if reviewers can confirm its proper functioning, since I cannot check this setup.