lib/util.sh: added pipe_delay (used as `cmd1 | { pipe_delay; cmd2; }`)

lib/util.sh: limit_stderr_cmd (): echo the command like echo_run so that callers don't have to separately call echo_run. this reduces clutter of the nested aliases, ensures that the command is always echoed outside of the inner stderr-limiter (which has a different log_level), and avoids echoing "limit_stderr_cmd" itself as part of the command name.

lib/util.sh: limit_stderr (): increase the log_level so that stderr of verbose commands can be turned off separately from the names of the commands themselves. it will now usually have log_level 2, indicating output that is useful primarily for debugging (this is the same as for shell function calls).

lib/util.sh: renamed log_stderr* to limit_stderr* to reflect that stderr is limited (i.e. controlled) rather than logged

lib/util.sh: echo_run_extern: renamed to log_stderr_extern since controlling stderr is its primary function

inputs/GBIF/MySQL_export: only include WHERE clause if $filter is set. support configuring LIMIT/OFFSET.

inputs/GBIF/table.run: table.tsv/make (): use new to_target to auto-delete $target on error

inputs/GBIF/table.run: table.tsv/make (): use new check_target_exists

lib/util.sh: make: added check_target_exists

lib/util.sh: moved $top_file* to runscripts/util.run because they only apply to runscripts