lib/sh/util.sh: logging: named it `log++`

lib/sh/util.sh: logging: verbosities: level 0: documented that log++ also suppresses external command output for full support of cron jobs

lib/sh/util.sh: logging: documented `make` equivalents of the various verbosities, where available. (many of the verbosities, such as level 1, are sorely needed in make to avoid excessive output.)

1. verbosities (and `make` equivalents):
2. 0: just print errors. useful for cron jobs....

lib/sh/util.sh: die_e(): benign errors: increase log_level so that a benign non-zero exit status will only be displayed at debug verbosities (2+) (it is confusing otherwise)

lib/sh/util.sh: try(): always run the command with benign_error=1 so that any die_e() doesn't prematurely indicate that a particular exit status was an error

lib/sh/util.sh: die_e(): support benign errors using $benign_error flag that should be logged as info messages instead of errors

lib/sh/util.sh: die(): documented that msg can't use $() (because it would reset $?)

inputs/bien_web/observation/VegBIEN.csv, unmapped_terms.csv: regenerated

lib/sh/util.sh: command(): 2>&$err_fd: add to _redirs after echoing command so it isn't echoed at the end of every command (since this redirection is frequently applied)

lib/sh/util.sh: sed: use case statement instead of test to determine flag letter, to easily allow matching multiple `uname` OSes or adding additional flag letters