Add options to include arrivals in the SAC header

[chad-earthscope]

Consider adding options to include arrivals in the SAC header.

Options accepting arrivals should accept both a time and a label.

The time should go into the 'a' or 't[0-9]' fields, and the labels should go into 'ka' and 'kt[0-9]' fields.

Traditionally first P goes into 'a' and S goes into 't0', and then other phases in t[1-9].