Delay at WP set by user in Grid ignored in Waypoint list, time calculation

This applies to ArduCopter: If a user constructs a flight plan using the Grid functionality, there is a field to enter a delay at each waypoint. This value never makes it into the flight plan; all WAYPOINT entries have zero for the delay parameter. Also, the total flight time calculation does not take these delays into account. Even if the delay times are only added as a first approximation (i.e. no acceleration/deceleration at the waypoint), it would be useful to have this factored in.

No files or tests are named. Start by tracing how the Grid flight-plan UI creates WAYPOINT entries and how total flight time is calculated; verify where the user-entered delay is lost. Done means waypoint delays are preserved and included in the total-time calculation, including an initial approximation without acceleration or deceleration.

Written by the indexing model from the issue text.