new pipeline to access social contact matrix data

Thanks to email report from Kornellius I learned about latest updates in socialmixr introducing contactsurveys package

Please place an "x" in all the boxes that apply
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- [x] I have the most recent version of this package and R
- [x] I have found a bug
- [x] I have a [reproducible example](http://reprex.tidyverse.org/articles/reprex-dos-and-donts.html)
- [x] I want to request a new feature

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Please include a brief description of the problem with a code example:

```r
# pak::pak("epiforecasts/socialmixr")
# pak::pak("epiforecasts/contactsurveys")
peru_doi <- "https://doi.org/10.5281/zenodo.1095664"
# peru_survey <- get_survey(peru_doi)
## --> We now recommend:
peru_survey <- contactsurveys::download_survey(peru_doi)
peru_data <- socialmixr::load_survey(peru_survey)
peru_data

socialmixr::contact_matrix(survey = peru_data,age.limits = c(0,20,40))

```

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