Implement a day-mask

[xivk]

Problem

Connections are now stored per 24h sorted by departure time. Each connection is stored individually, this means that storing 2 days of connections takes 2x the storage. This doesn't scale properly for some of the use cases this library is meant to support:

• Planning routes in the future.
• Supporting offline routing on the planned schedules.
• ...

Solution Proposal

We should add a mask to the connections instead of a date. That mask describes the schedule that determines when the connections are active.

[pietervdvn]

A daymask could look as:

"Connection departs at 10:00, from station A to station B, has tripId 123" * ( DATE0, DATE1, DATE2, ....)

The exposing API (towards the algorithms, that is) would boil down to enumerating all these connections.

Adding realtime info can be done by creating an exceptions-object. This exceptions object would enumerate connections as well, but amend this enumeration: delayed connections should be given on later, earlier departures given earlier.

For this, the 'RealTime' object can keep a list of 'exceptions', sorted by original and new departure time. This way, the enumerator should be able to quickly detect when a connection (from the regular enumerator) should be dropped or when it should be extra included.