Add "impatience_factor" option to weight transfer search by time as well as delta-v

[maneatingape]

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Is your feature request related to a problem? Please describe.

Sometimes a transfer that is only slightly lower (e.g. by 1 m/s or so) but much further in the future is selected, resulting in more time warping than necessary.

Describe the solution you'd like

Create a setting with units of m/s^2. Then when comparing transfers the total adjusted cost is the raw deltav + the time difference from now. This will weight transfers that occur sooner, in order to prevent a transfer that is only very slightly cheaper but much further in the future from taking precedence.

For example: impatience_factor = 5e-6 = 0.000005

Then if there are 2 transfers:
Current time: Y1 D1
Transfer 1 => Time Y2 D1 => Raw deltav: 1000 => Adjusted deltav: 1046
Transfer 1 => Time Y2 D1 => Raw deltav: 999 => Adjusted deltav: 1091

Describe alternatives you've considered

Use existing earliest_departure and search_duration setting to limit searches to windows. User can search within each window then select transfer using arbitrary criteria.