add -f <from-address> option.
remove CIA notification support, never seen anyone use it. raises eyebrows in a code review ("is this script sending my commits to some api...?")
option change: -t <to-address> instead of -m <to-address>
add -m mailer option to override default of sendmail. useful for testing.
use the git config key 'mail.to' for the -t <to-address> option.
code cleanup: use main() instead of file scope code; kill redundant usage info in comment; don't mess with @ARGV global.
eliminate perl sub prototypes. this is not C.
code cleanup: logically reorder functions, higher-level stuff first.
fix Subject: / email body separation
check exit status of git commands that pipe output to us. die and report non-zero exit codes.