added bin/make, which runs make, hiding verbose messages about making included Makefiles. this should be used in preference to plain make, to avoid excessive log messages that prevent the user from seeing the core commands that are being run.

lib/sh/util.sh: added no_PATH_recursion(), which allows running a system command of the same name as the script

lib/sh/util.sh: added PATH_rm(), which removes components from the PATH

lib/sh/util.sh: added $top_dir_abs, $top_dir_orig

bugfix: lib/sh/util.sh: command(): use `builtin command` instead of `exec` so that options like -p (reset PATH) work properly. also, the command builtin it overrides is designed to be used with more than just external commands, and command() should not impose additional limitations.

lib/sh/util.sh: added self_sys alias, which uses only system utilities (`command -p`) instead of the current PATH

lib/sh/make.sh: make(): at verbosity < 3, hide messages about making included Makefiles. this makes the make output much more readable when a Makefile contains an include statement, because there won't be a ton of log messages every time a Makefile is included. this filtering is so useful that it probably makes sense to run make for any of our Makefiles using `lib/runscripts/util.run make ...` instead of plain make. compare e.g. `make inputs/ACAD/Specimen/map.csv` (53 lines of output) and `lib/runscripts/util.run make inputs/ACAD/Specimen/map.csv` (17 lines of output, 1/3 as much).

lib/sh/util.sh: log++: before cmd: documented that you need to use "log++" instad of log++ to avoid using the log++ alias, which prepends a log_local call. omitting the quotes is generally not a problem, but when there is another command wrapping the log++, you need the "" to avoid the wrapper applying to log_local's declare call instead.

lib/sh/util.sh: log++: before cmd: documented how to use it as `log+ #` when incrementing multiple log_levels at once (this is a better method than `"log++" "log++" ...`)

lib/sh/util.sh: log++: before cmd: documented that you need to use it as `"log++" "log++"` when repeating it multiple times