non-ASCII characters in `R/camR_functions.R`.

[SanderDevisscher]

checking code files for non-ASCII characters ... WARNING
Found the following file with non-ASCII characters:
R/camR_functions.R
Portable packages must use only ASCII characters in their R code and
NAMESPACE directives, except perhaps in comments.
Use \uxxxx escapes for other characters.
Function ‘tools::showNonASCIIfile’ can help in finding non-ASCII
characters in files.