Parse timestamps from pull to pull to get accurate start/wait times

[seanpeters86]

For each event that is followed by another event we need to set the proper first= syntax to start the raid event at the right time, and follow it with the proper wait duration.

For example:

1. raid event 1 lasts 40 seconds with a 20s gap
2. raid event 2 lasts 20s

raid_event+=x,duration=40
raid_event+=y,first=60,duration=20