Issue#16

[Degoot-AM]

This PR adds:

1 - age_limits as optional argument to contact_matrix
2- rename columns and rows to meet style of {socialmixr}

[Bisaloo]

Point 1 is addressed by #20.

For point 2, I would prefer to:

• not have socialmixr as a dependency
• deliver the matrices exactly as provided in the original paper since they is the stated scope of the paper

The best option is likely to add this feature in the shared contactmatrix class (socialcontactdata/contactmatrix#16), so all packages, including this one when #2 is addressed, can benefit from this feature.

The workflow would then be:

contactdata::contact_matrix(my_country) |>
  contactmatrix::merge_age_groups(new_groups = c("[0,10)", [10, 25)", "[25, 100)"))