Changes as follows:
 - split gap filling into L4 (meteorological drivers) and
   L5 (fluxes), partitioning is now L6
 - associated changes to the template control files
 - implemented gap filling from BIOS2
 - implemented "Import" at L4 to allow MODIS data
   to be imported into the OzFluxQC path
 - implemented QC checks at the start of L4 and L5
Updated version number to V2.8.4.