web/links/index.htm: updated to Firefox bookmarks: updated favicons

web/links/index.htm: updated to Firefox bookmarks: modifying a running shell script: updated to document that `svn up` actually does use two-stage save automatically

web/links/index.htm: updated to Firefox bookmarks: PostgreSQL: added operator classes. added backups: filesystem-level backup, continuous archiving, WAL logging, etc. virtual collaboration: updated annotations.

*{.sh,run}: runscript targets: use begin_target instead of echo_func so the target name is properly echoed. note that this requires using with_rm so that $rm is properly progagated to applicable invoked targets. (previously, $rm was progagated to all invoked targets. note that with_rm only works inside a runscript target that starts with begin_target.)

web/links/index.htm: updated to Firefox bookmarks: Firefox: added instructions for enabling security.password_lifetime and making all tabs load when the browser is opened

web/links/index.htm: updated to Firefox bookmarks: Google Drive: listed bugs that make it very difficult to use (the need to re-download all files when reconnecting a client to an account). added recommendation not to use it (unstable).

web/links/index.htm: updated to Firefox bookmarks: PostgreSQL: query planner: documented how to prevent incorrect query plans (`SET enable_seqscan = off;`, etc.)

web/links/index.htm: updated to Firefox bookmarks: PostgreSQL: query planner: documented that incorrect query plans are an ongoing bug in Postgres, because it does not support index hints and by default does not follow the join order. specifically, Postgres often does the following things in query plans which should normally never be done:...

web/links/index.htm: updated to Firefox bookmarks: PostgreSQL: added description of join_collapse_limit config param (which should be turned off, although it is on by default). added links for using TIDs ("the fastest possible access to a single row").

web/links/index.htm: updated to Firefox bookmarks: PostgreSQL: added links for troubleshooting autovacuuming (which can slow queries down significantly when it isn't happening for any tables)