*run: added include guards

bugfix: lib/util.run: added include guard to prevent issues in "diamond includes", where a runscript includes two runscripts and each includes util.run, causing the second include of util.run to reset any methods overridden in the first included runscript. this prevents util.run from being included twice in the first place.

lib/util.run: added include_guard_var (), self_not_included () for use by path-based include guards

lib/util.run: echo_stdin (): print a separator before and after the echoed output to help distinguish it from other verbose output

lib/table.run: use new local.run instead of defining $bin_dir, etc. itself

lib/util.run: echo_export (): run the export builtin using `builtin` to avoid recursively calling any export alias or function defined by the user (e.g. `alias export=echo_export`. this causes util.run to be idempotent, such that it can be included multiple times without causing problems due to the redefinition of functions, vars, etc.

added lib/local.run, which links to locally-available resources such as $bin_dir

lib/table.run: added mysql (), mysql_ANSI ()

added web/links/index.htm containing Firefox bookmarks exported to HTML. CSS style information has been added to fix default HTML tag formatting, improve readability, and handle the Firefox bookmarks format. <dd> tags have been manually closed where HTML would not auto-close them properly. note that these changes must be reapplied each time the bookmarks file is reexported (`svn di` will show the changes to make).

lib/table.run: run mk_esc_name for $schema, $table