*{.sh,run}: use shorter `test` instead of `test -n` and `test !` instead of `test -z` (http://www.gnu.org/software/bash/manual/bash.html#Bourne-Shell-Builtins > test)

lib/sh/util.sh: echo_cmd (): don't include leading extern because it clutters up the output and is implied by the log_level

lib/sh/util.sh: to_file (): run echo_func and `echo_vars stdout` to show what file the output is going to, since this information (i.e. redirects) isn't included in the logging output for the command itself

lib/runscripts/table.run: remake_VegBIEN_mappings (): added public_schema_exists check, ported from lib/import.sh

lib/sh/local.sh: added public_schema_exists (), ported from lib/import.sh

*{.sh,run}: use new echo_stdout instead of echo_stdin where applicable, for clarity

lib/sh/util.sh: added echo_stdout (currently just an alias of echo_stdin, because they are usable for the same purpose)

/run: moved geoscrub_input export into separate geoscrub_input/make () target

lib/sh/db.sh: pg_export_table_to_dir_no_header (): use to_file so that the file is autoremoved in case of error

lib/sh/util.sh: let (): renamed to let! so that let can still be used to evaluate whether a numeric value is 0 (yes, an ! is allowed at the end of a command name)