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.

bugfix: /README.TXT: Maintenance: to synchronize a Mac's settings with my testing machine's: sync ~/Dropbox/svn/ (the no-unversioned-files working copy) separately from the rest of the files, because .svn/ is now excluded by /.rsync_ignore, so that `svn up` needs to be used to keep the .svn/ dirs in sync. note that .svn/ should generally not be synced between machines, because they may use incompatible versions of the svn working copy format.

/README.TXT: Maintenance: to synchronize a Mac's settings with my testing machine's: use new bin/sync_upload (with $sync_remote_subdir) so that per-dir .rsync_ignores are processed, and to use the default $sync_remote_url

lib/sh/local.sh: $sync_remote_url: allow user to override just the sync subdir (not the whole URL) in $sync_remote_subdir. this is useful e.g. for backing up the Mac's files to jupiter.

/README.TXT: Maintenance: to synchronize vegbiendev, jupiter, and your local machine: use new bin/sync_upload instead of specifying all the filter patterns manually. this replaces several `put` commands with various filters with just a bin/sync_upload each on vegbiendev and your machine (in overwrite=1 mode to force a complete sync).

bugfix: backups/.rsync_filter.download: need to prevent existing backups from being deleted on the local side, too, by changing hide patterns to exclude

lib/sh/sync.sh: upload(): make put's $subpath option relative to the currdir instead, like the --include paths. note that $subpath unfortunately can't be used in subdirs at this point because it will cause rsync to ignore the .rsync_ignores and .rsync_filters in parent dirs, including the essential .rsync_ignore in the sync root dir.

/README.TXT: removed unnecessary `env` before kw params, which are treated as such whenever they appear before a command name