Resolve initial CRAN feedback

[medewitt]

• Add single quotes around package and software names

• Add dois to any methods cited

• Please ensure that your functions do not write by default or in your examples/vignettes/tests in the user's home filespace (including the package directory and getwd()).

• You are using installed.packages() in your code. As mentioned in the notes of installed.packages() help page, this can be very slow. Therefore do not use installed.packages

[medewitt]

Closed with #8