…ection of code.

…unication, presume xios was anticipating further setup)

…it round but not necessary to proceed.

…es appropriately (ifcore already available, don't search)

nextsim build fails due to incorrect order of libraries

-lxios needs to come before -lnetcdf

also

for gnu compiler we need -lgfortran and for intel compiler we need
-lifcore

TODO:

Findxios in conjuction with the CMakeLists.txt needs fixing still so
that it can work when xios is not installed.

I have manually changed lib ifcore to lgfortran. This will need to fixed
properly for intel and gnu compiler and not hard-coded.

this is a temporary fix.

The order of libs is also incorrect for XIOS_LIBRARY_LIST. xios depends
on netcdf so it should come second.

There was an erroneous ::Xios for the constructor when creating
xios_handler.

I have updated the ubuntu install and setup for XIOS and nextsimdg

I have removed unnecessary packages and hopefully xios will now build.

I have updated and simplified the Xios class

We have methods to get/set common variables:
* Calendar origin
* Calendar start
* Calendar timestep

There are some initialization method and an isInitialized function to
verify.

I have simplified the string conversion string for datetime