lib/sh/db.sh: mk_select: constructed queries: support custom columns list using $cols

lib/sh/db.sh: mk_select: constructed queries: support WHERE clause using $filter

lib/sh/util.sh: echo_stdin(): don' increase the log_level, because the input being sent to the command (which is usually a set of interpreted commands itself) is necessary to fully know what action is being performed

bugfix: lib/sh/local.sh: add a manual errexit for $() exprs by embedding them in just a var assignment (without local or declare), whose exit status will then equal the of the $(). a `|| return` also needs to be added because errexit does not work on assignment statements. this commit adds them for func_loc(), echo_func(), canon_rel_path(), set_paths(), save_cache, cached realpath(), local.sh global vars

lib/sh/util.sh: shell-variable-based caching: usage: updated alias names

web/links/index.htm: updated to Firefox bookmarks. regenerating also removed extra <a name=...> tags that were added when running index.htm.run on an already-processed index.htm.

bugfix: lib/sh/util.sh: `set -o`: need a -o before every option to set

lib/Firefox_bookmarks.reformat.csv: add HTML anchors for external links' names: hyperlink the added anchors as clickable paragraph marks (like Redmine), which take you to the HTML anchor. this is analogous to the clickable folder names which take you to their anchors.

lib/Firefox_bookmarks.reformat.csv: add HTML anchors for external links' names, in addition to their URLs

bugfix: lib/Firefox_bookmarks.reformat.csv: add HTML anchors for external links' URLs: use .*? instead of .* to match the contents of the <A> tag before the HREF