Implement SingleOrMulti pattern for all traces/objects #196

This is a giant refactor and may be something to da after the 2.0 release. in #193 i implemented this for Bar traces and the respective Chart constructors.

Once this issue gets tackled i suggest adding checklist items as below and converting them to issues

Trace progress

• Implement SingleOrMulti pattern for bar trace/chart constructors (see Handle properties that can be either single or multiple values #193)

Object progress

• Implement SingleOrMulti pattern for Marker (see Handle properties that can be either single or multiple values #193)