/README.TXT: Full database import: disk space: documented that the entire disk again gets used long after the beginning of the import, when only a few datasources are running (ie. it definitely seems to be a recent bug in Postgres, and not a latent problem)

/README.TXT: Maintenance: added task to regularly re-run full-database import so that bugs in it don't pile up. it needs to be kept in working order so that it works when it's needed.

/README.TXT: Full database import: added steps to manually reimport the applicable datasources if there are errors due to exceeding available disk space

/README.TXT: Full database import: removed extra `ssh -t vegbiendev.nceas.ucsb.edu` before "upload logs", because the previous steps also occur on vegbiendev

/README.TXT: Notes on system stability: added recommendation to maintain a snapshot copy of the VM as it was at the last successful import, for fallback use if a system upgrade breaks anything. system upgrades on the snapshot VM should be disabled completely, and because this will also disable security fixes, the snapshot VM should be disconnected from the internet and all networking interfaces. (this is an unfortunate consequence of modern OSes being written in non-memory-safe languages such as C and C++.)

/README.TXT: Full database import: disk space: documented that a higher high-water mark actually occurs later in the import, so that the disk usage issue actually remains a problem after the very beginning

fix: /README.TXT: Full database import: disk space: increased the minimum free space recommendation to 1 TB, because analysis of the disk usage during the beginning of the import shows that actually close to the entire amount is being used. however, this problem is normally undetectable unless the disk space is specifically checked, because it only manifests itself if the available disk space is exceeded completely.

/README.TXT: Full database import: documented that the beginning of the import should be scheduled at a time when the DB will not be needed for other uses, because vegbiendev will be slow for the first few hours of the import due to the import using all the available cores

/README.TXT: Full database import: documented that CPU load warning e-mails can safely be ignored. they happen because the parallel imports use all the available cores.

fix: lib/common.Makefile: $(nice): use an increment of +10 instead of +5 because +5 still leaves the shell sluggish