lib/sh/util.sh: added sys_cmd(), which runs a system command and allows running a system command of the same name as the script

lib/sh/util.sh: added echo_builtin()

inputs/.rsync_ignore: test*.xml: turn on syncing again, but always treat the local side of the sync (starscream or vegbiendev) as the authoritative copy since they are the machines the tests can be run on

/.rsync_ignore: temp files: hide them on upload so that they are never synced to jupiter. hiding is different than unidirectionally exclude'ing them, because it also causes them to be deleted on the destination if they were uploaded in previous syncs.

inputs/VegBIEN/TWiki/.rsync_ignore: /**: turn syncing back on, but only allow it unidirectionally from vegbiendev->jupiter->starscream to avoid clobbering the live site or the jupiter backup. this is probably the only dir whose authoritative copy is always on vegbiendev. for all other dirs, edits can be made wherever convenient, so no copy is authoritative and no sync directions need to be restricted.

/README.TXT: Maintenance: synchronization: fixed whitespace

inputs/.rsync_ignore: install.log.sql: only exclude this on starscream (the local machine), using new machine-specific .rsync_filters, so that vegbiendev's copies of this will be backed up

lib/sh/sync.sh: upload(): .rsync_filter: also support machine-specific filters, for cases when different machines produce the same file (e.g. a log file) but only one machine's copy should be backed up

/README.TXT: Maintenance: to synchronize a Mac's settings with my testing machine's: removed filters that are now handled by .rsync_ignores

added inputs/GBIF/_src/.rsync_filter.upload,download to prevent old versions of GBIFPortalDB-*.dump.gz from being downloaded to the local machine, while keeping them on jupiter. this avoids the need to store these files in ~/Documents/BIEN/large_files/ with symlinks from inputs/GBIF/_src/ to exclude them from the sync.