bugfix: bin/import_all: now that always using log files to fix output clutter, need to delete created logs if logging is turned off

bugfix: bin/import_all: don't errexit if a background process is Ctrl-C'd

bugfix: bin/import_all: was run without initial "." test: don't exit nonzero because this will close the subshell

bugfix: bin/import_all: ensure that this is run in a subshell, which is needed so errexits don't close the terminal window

bin/import_all: documented that this must be run in a subshell (obtained by running `$0`)

bugfix: bin/import_all: need to always use log files for background processes

fix: bin/import_all: Source/import: don't use by_col=1 for this because it's slower for small #s of rows. by_col mode is no longer needed for metadata-only tables because these tables now have a single empty row so that they also work in row-based mode.

fix: bin/import_all: hidden srcs: use with_all for this to avoid needing to list every source, and to display the backgrounded command with the variables substituted

bin/import_all: TNRS, geoscrub: integrated into the list of metadata sources

bin/import_all: TNRS, geoscrub: use import rather than publish because the non-imported tables have now been excluded