removed duplicate variable declaration
Major update of surface physics

* iterative relaxation for surface temperature improves turbulent heat fluxes
* encapsulated subroutines for heat flux calculations
* partitioning of melt into melted ice and melted snow
* same for refrezzing (refrozen rain and melt)
* temperature update different for land and ice (no melted ice over land)
* added functionalityu for REMBOv2 handling of 2m air temperature: introduced weighting functions
update of examples w.r.t. previous update of surface physics

* land/ice/ocean mask now also integer mask