We've now (out of necessity) replaced various types from std::chrono with our own. This currently has the effect that many of our interfaces mix types from rdf4cpp and std::chrono. This leads to fundamental inconsistency in interfaces.

I think there are two ways forward:

1. Use std::chrono whenever possible, also in interfaces.

• Pros:
  • makes clear whenever we use chrono
• Cons:
  • interface inconsistency, and maybe confusion where to search for types (sometimes its chrono, sometimes its not. With no obvious rules, except for "chrono didn't work".

2. typedef almost all types from std::chrono into the rdf4cpp namespace (or a subnamespace)

• Pros:
  • when we need to replace more types in the future (due to still unknown requirements, the change will be less prone to breaking code)
  • the interface will be consistent, and it will be obvious where to types live (in rdf4cpp)
• Cons:
  • we hide the fact that we actually use chrono somewhat, which might be confusing