Enable route_pattern to also exclude selection

[mpadge]

Currently only works as a positive grep match. Should also add an invert_match = FALSE parameter that, when TRUE, uses grep(..., invert = TRUE) to exclude the matched items. What should it be called?

• [ ] invert_match to match the invert parameter of grep itself, which is in turn called that because that just adds the -v flag to the grep library call which is described as "invert call".
• [ ] exclude_match because that is perhaps more directly informative

ping @AlexandraKapp

[AlexandraKapp]

hm, both arguments seem valid. 🤔 how about a third option: invert_route_pattern = FALSE to make it more apparent that the parameter belongs to the route_pattern within the gtfs_timetable function?

[mpadge]

Good idea, but how about an even better one: That commit just allows a "!" to be put at the start of any route_pattern argument in order to invert/exclude it.