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

lib/sh/util.sh: die(): documented that its msg can use $?, because it has not yet been overridden by another command

lib/sh/util.sh: die_e(): use die(), which performs the necessary save_e/rethrow. this requires using $? instead of $e for the exit status, because $e has not yet been set.

lib/sh/util.sh: inlined log_e() into die_e() because that's the only place it's used