zcip: code size optimizations, improved help text and comments

function                                             old     new   delta
packed_usage                                       24750   24787     +37
run                                                  658     655      -3
pick                                                  40      34      -6
arp                                                  186     177      -9
zcip_main                                           1402    1356     -46
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(add/remove: 0/0 grow/shrink: 1/4 up/down: 37/-64)            Total: -27 bytes

2 files changed