Memory/RAM solutions

[CeresBarros]

We'll need to think about how and "where" to deal with RAM limitations, when dealing with e.g. many climate projections.
At the moment, in a 32GB machine, climr runs out of memory if all GCMs/periods/scenarios are requested (process_one_raster runs out of memore when extracting the climate values)

Options are to (not mututally exclusive):

1. (partially) deal with these in climr
2. deal with these externally to climr (e.g. in the modules that will need to extract cliamte projections)
3. have climr warn the user about memory limitations (implemented in climr@out-of-memory-extract)

[CeresBarros]

currently implementing options 2 and 3