lib/sh/util.sh: command(): made usage message an end-of-line comment

lib/sh/util.sh: inlined limit_log_fd into command() since it's only used once

lib/sh/util.sh: log_err(), log_info(): use bolder symbols (*, #) to make the symbol stand out visually from the line of | above and below it

lib/sh/util.sh: $verbosity: lowered the default from 3 to 2 because level 3 output (vars, etc.) is too verbose for the default output and is only needed for debugging

lib/sh/util.sh: $log_level_indent: added space after | to visually separate the nesting levels and make the output look like an expandable tree (similar to a filesystem browser tree)

lib/sh/util.sh: log_custom(): replace every non-whitespace character of $log_indent, and the first character of PS4, with the symbol, to make the symbol stand out on the line instead of the |||... before it

lib/sh/util.sh: removed no longer used stdout2log_fd(). set $cmd_log_fd instead.

lib/sh/util.sh: set $log_level_indent to | because this visually connects commands at the same indent by effectively connecting their + prefixes with a line of |

lib/sh/archives.sh: zip(), unzip(): added missing echo_func

lib/sh/util.sh: command(): use just one control var $cmd_log_fd instead of three flags (limit_log_fd, limit_stdout, stderr_is_errors) that indicated various common fd configurations. this is much clearer (you state which fd the common uses as its logging fd), more configurable (the logging fd can be any fd, not just 1 or 2), and more automatic (redirecting fd 2 to err_fd happens automatically if it isn't used for logging).