use `roxygen2` blocks to document your functions & rebuild the documentation

[SanderDevisscher]

A few issues should be fixed by implementing roxygen2 blocks to your functions. Finally each function should contain the following blocks:

• #' %a name%
• #' %a short description what the function does%
• #' @param %name% %description% for each of the function parameters
• #' @return %a short description of what the function returns% if relevant
• #' @export If the function should be found outside the package
• #' @examples /don't run{%some examples} if relevant

Make sure all relevant text from old rd's is included.

For every function you should do the following:

• add roxygen2 blocks
• remove relevant old rd's
• run devtools::document() or roxygen2::roxygenise()

FYI this can be done in bulk