New stucture in resolution processing with higher performance

[matzegoebel]

Currently processing of each resolution starts with the high resolution input of the shell scripts (from now on called raw input), instead of using the output of the previous, lower resolution. This can be optimized with the following new structure:

• Sort resolutions by increasing time step size
• Start with highest resolution: full program in extra function on raw input
• Take output of this resolution for next lower resolution if the cell method (cm) is compatible with the previous one (otherwise process full program on raw input): most global and variable attributes should be still correct, process variable with cdo command and change time and time_bnds (create if previous resolution had cm 'point') variables, 'res' global attribute and filename and location.
  Note that also e.g. the cell method for seasonal/monthly processing 'maximum within days time: mean over days' is compatible with the daily cell method 'maximum'. In case of this special cell method, the script should check if the daily data are available with the correct cell method and if not create it at least temporarily (as is done now).
  If the seasonal processing uses the monthly output with cell method 'mean' the possibly unequal length of the different months should be taken into account.