Improve function documentation

[ClaytonJY]

The current function documentation in R/RQt.R should be improved, following guidelines from Hadley.

Some outstanding issues I see:

• input/output types not clearly specified
• short titles and no long descriptors for some functions
• all the Descriptions (second line) start with the name of the function
• all examples are both ran and not ran; this is unnecessary. Because of the complex nature of some of these functions and issues with pathing, it's fine to have not-quite-valid code listed in \dontrun{}; more helpful, complex examples can be in demos/vignettes (see Convert Examples to demos or vignettes #18).