Netcdf

[aosprey]

Replace all netcdf code, in preparation for parallelisation.

• Use XIOS for restart reads, can reuse file/field defintion from restart write.
• Simpler interface for ancillary reads.
• Make use of netcdf interface to i) cast input float data into 8-byte reals, and ii) read 2d/3d fields into lower dimensional arrays.

Note that not all of these ancillary reads have been tested. Untested:

• mckpp_initialize_couplingweight()
• mckpp_initialize_advection()
• mckpp_initialize_optics()
• mckpp_read_sst()
• mckpp_read_ice()
• mckpp_read_heatcorrections()
• mckpp_read_saltcorrections()
• mckpp_read_temperatures()
• mckpp_read_salinity()

[aosprey]

Also, this changes results from main. I think this occurs because we read data into 8 byte variables, whereas previously we read to 4-byte temporary variables and then copied into 8-byte arrays. In particular the vertical interpolation was done with the 4-byte arrays previously, which does change the results.