Request ability to group multiple flights into a single trip

[bovine]

It would be useful to allow the ability to select multiple flights and combine them into a single "trip" for the purposes of accounting cross-country milestones or tracking expenses.

Currently if a long multi-leg trip is logged had been logged as multiple separate flights, they are considered differently than if they had just been logged as a single flight with the multiple destinations listed in the route field.

[bovine]

Note that this would help to provide feature parity with other apps, such as LogTen Pro, and one user I've communicated with has indicated that this was a motivating feature benefit for his flight records.