lib/sh/util.sh: use `minor=1 echo_func` instead of echo_minor_func because the syntax is simple enough that you don't need a separate alias for it

lib/sh/util.sh: echo_func: support using minor=1 to increase the log_level that the function call is echoed at. use this in echo_minor_func.

lib/sh/util.sh: echo_*func aliases: use simpler && syntax (with `|| true` to prevent errexit if the condition is false) instead of an if statement. this also allows prefixing the alias with var definitions.

lib/sh/util.sh: echo_*func aliases: use simpler && syntax (with `|| true` to prevent errexit if the condition is false) instead of an if statement. this also allows prefixing the alias with var definitions.

lib/sh/util.sh: echo_func: only indent if the function call was displayed. this avoids confusing extra whitespace when a function call causes an indent but the function call itself isn't printed.

bugfix: lib/sh/util.sh: echo_minor_func: need to include "$@" in echo_func() call

lib/sh/util.sh: echo_func(): added usage

lib/sh/util.sh: echo_func: added usage

lib/sh/util.sh: $log_level_indent: changed to a single space rather than two, to avoid very deep indents as the call tree becomes more deeply nested. due to the + at the beginning of every line, a single space is enough to visualize the structure of the call tree (unlike source code, which requires more whitespace because it doesn't have a call tree structure).

lib/sh/util.sh: echo_*func aliases: increase the indent for the duration of the function call. this causes function calls to be displayed in an indented call-tree structure, which makes the verbose output much easier to understand.