GTFS Functionality

[sebhoerl]

In all scenarios except IDF, we have multiple GTFS feeds. Currently, one can provide a semicolon-separated list of feeds to be merged.

• Allow the GTFS path to be a list to avoid the awkward format with semicolons
• Check if this works well with validation / devalidation, otherwise this might need to be adjusted in synpp (in terms of hashing the config value if it is a complex object)

Futhermore, this often brings problems because sometimes GTFS schedules cannot be found that cover the same period of time. Since with pt2matsim we can either choose the day with most services (default) or a fixed day, we have situations in where some feeds are simply ignored because they don't cover the selected day. We already have code to unify the schedules, i.e., find all "wednesdays" (or whatever day is requested) and find in each feed the one with most active lines, and then shift all of those wednesdays to a specific date that is later used by pt2matsim.

• Integrate the schedule shifting functionality into the pipeline

[sebhoerl]

Closing this in favor of #223