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)

lib/Firefox_bookmarks.reformat.csv: "page's description": changed to "page's own description" to clarify that this is a description provided by the page itself

web/links/index.htm: updated to Firefox bookmarks: PostgreSQL: added links for error reporting levels and how to hide stack traces in psql. SQL: added links for recursive queries, which can be used to traverse hierarchical (parent-pointer) tables.

web/links/index.htm: updated to Firefox bookmarks: PostgreSQL: difference between STABLE and IMMUTABLE: functions that depend on the search_path: clarified that the confusing effects of using IMMUTABLE for one of these functions are only noticeable if the function is called on only constant values in a PL/pgSQL function (in which case the wrong search_path (the one in effect at create time) will be used)

web/links/index.htm: updated to Firefox bookmarks: PostgreSQL: added explanation of the difference between STABLE and IMMUTABLE, and common pitfalls in using IMMUTABLE when you should use STABLE. svn: added troubleshooting steps for running `svn upgrade` after the last Mac system update, which upgrades svn.