Errors in running code in vignettes:
when running code in ‘Follow-up.rnw’
  ...

> library(Epi)

  When sourcing ‘Follow-up.R’:
Error: package or namespace load failed for ‘Epi’ in dyn.load(file, DLLpath = DLLpath, ...):
 unable to load shared object '/Volumes/XT3/Builds/R-dev-web/QA/Simon/packages/el-capitan-x86_64/Rlib/3.4/Rcpp/libs/Rcpp.so':
  dlopen(/Volumes/XT3/Builds/R-dev-web/QA/Simon/packages/el-capitan-x86_64/Rlib/3.4/Rcpp/libs/Rcpp.so, 6): Library not loaded: /Library/Frameworks/R.framework/Versions/3.4/Resources/lib/libc++.1.dylib
  Referenced from: /Volumes/XT3/Builds/R-dev-web/QA/Simon/packages/el-capitan-x86_64/Rlib/3.4/Rcpp/libs/Rcpp.so
  Reason: image not found
Execution halted
when running code in ‘simLexis.rnw’
  ...

> library(Epi)

  When sourcing ‘simLexis.R’:
Error: package or namespace load failed for ‘Epi’ in dyn.load(file, DLLpath = DLLpath, ...):
 unable to load shared object '/Volumes/XT3/Builds/R-dev-web/QA/Simon/packages/el-capitan-x86_64/Rlib/3.4/Rcpp/libs/Rcpp.so':
  dlopen(/Volumes/XT3/Builds/R-dev-web/QA/Simon/packages/el-capitan-x86_64/Rlib/3.4/Rcpp/libs/Rcpp.so, 6): Library not loaded: /Library/Frameworks/R.framework/Versions/3.4/Resources/lib/libc++.1.dylib
  Referenced from: /Volumes/XT3/Builds/R-dev-web/QA/Simon/packages/el-capitan-x86_64/Rlib/3.4/Rcpp/libs/Rcpp.so
  Reason: image not found
Execution halted
when running code in ‘yll.rnw’
  ...

> library(Epi)

  When sourcing ‘yll.R’:
Error: package or namespace load failed for ‘Epi’ in dyn.load(file, DLLpath = DLLpath, ...):
 unable to load shared object '/Volumes/XT3/Builds/R-dev-web/QA/Simon/packages/el-capitan-x86_64/Rlib/3.4/Rcpp/libs/Rcpp.so':
  dlopen(/Volumes/XT3/Builds/R-dev-web/QA/Simon/packages/el-capitan-x86_64/Rlib/3.4/Rcpp/libs/Rcpp.so, 6): Library not loaded: /Library/Frameworks/R.framework/Versions/3.4/Resources/lib/libc++.1.dylib
  Referenced from: /Volumes/XT3/Builds/R-dev-web/QA/Simon/packages/el-capitan-x86_64/Rlib/3.4/Rcpp/libs/Rcpp.so
  Reason: image not found
Execution halted