Takes a completed metFile object (generated via prepareMet or
loadMet) and writes it to disk.
writeMetFile(fileName, met)The file name to write to.
The metFile object to write.
Note the file will not be written if the met object is missing required
information such as latitude, tav or amp. Note that while longitude is required
in prepareMet, it is not strictly required by APSIM and thus is
optional here. However, it is best practise to include it so it will remain
mandatory when building a met file via prepareMet.