bugfix: lib/sh/util.sh: limit_stderr(): switched back to running inc_log_level inside limit_stderr(), because it should only apply during the function for use by can_log. documented why inc_log_level needs to be inside limit_stderr().

bugfix: lib/sh/util.sh: limit_stderr(): stdout2stderr mode: only limit stdout, since stderr may contain error messages (which should always be displayed)

bugfix: lib/sh/util.sh: limit_stderr_cmd(): need to load new aliases before it so limit_stderr is expanded

bugfix: lib/sh/util.sh: limit_stderr alias: need to inc_log_level before rather than after limit_stderr(), so that can_log uses the right verbosity (previously, inc_log_level was part of limit_stderr() itself, but was moved to the alias because its effects were needed outside the function)

lib/sh/util.sh: stdout2stderr(): fixed doc comment after space-before-() search-and-replace

lib/sh/util.sh: usage(): use `return` instead of `(exit ...)`

lib/sh/util.sh: verbose output: put commands into subsections

lib/sh/util.sh: echo_run(): factored prep code out into echo_run_prep alias, which can also be used in commands that mimic it, such as limit_stderr_cmd()

bugfix: lib/sh/util.sh: limit_stderr(): moved indent to echo_run prep, because it only applies to commands invoked with echo_run

bugfix: lib/sh/util.sh: limit_stderr(): need to apply inc_log_level in the caller so it won't get rolled back at the end of the function