lib/util.sh: added exception-handling (i.e. error-suppressing) functions

bugfix: lib/util.sh: echo_func alias: moved it outside the include guard because the unalias statement is needs to be outside the include guard, and therefore so does the alias statement in order to always restore the alias

lib/util.sh: renamed echo_func_ () back to echo_func () and instead add an unalias statement before the if statement containing the function definition. this is necessary because if statements are "compound commands", which have aliases expanded when their definition is read (i.e. at the beginning of the if statement, for the entire if statement), not when they are executed, and any aliases for function names in them need to be unaliased before the if statement containing the function definition. this is necessary even if the if statement is not executed, because the expansion of such aliases will cause syntax errors in the parsing of the if statement itself....

lib/util.sh: added unalias () override, which doesn't produce an error if the alias is undefined

bugfix: lib/util.sh: renamed echo_func () to echo_func_ (), because you apparently can't have a function with the same name as an alias, even if the function is defined before the alias and an include guard prevents the function from being defined again after the alias is set. there may be some kind of alias-expanding preprocessing pass that bash only does in script mode, or maybe there is some other problem related to our use of aliases inside if statements.

*{.sh,run}: changed echo_func to an alias that includes the "$", so that callers don't need to specify the "$" manually. although the original echo_func function is still there, callers need to switch over to the alias at the same time as it's defined because otherwise the "$@" would be doubled, since echo_func refers to the alias instead.

lib/util.sh: added set_make_vars alias, for use with make-target-style shell functions

lib/util.sh: mysql_cmd (): interpret an empty string for $user, $database as if they were unset

bugfix: lib/util.sh: mysql_cmd (): add --tables after specifying --databases so that future unnamed arguments are correctly interpreted as tables

bugfix: lib/util.sh: mysql_cmd (): need to use `--databases ...` rather than `--database=...` to specify the database as a named argument