Changes as follows:
 - changed levels of processing to better reflect the workflow;
   - L3 is QC and post-processed as before
   - L4 is gap filled meteorology
   - L5 is gap filled fluxes
   - L6 is partitioned
 - implemented importing of data at start of L4
 - implemented ingestion of MODIS EVI data
   - reformat of MODIS output from DINGO
 - sundry other fixes;
   - changes to main GUI (dropped L4 buttons, now use menu)
   - can't remember the rest