Add quickplot_*() functions

[MonikaFu]

As a user I want to able to use the package with a minimal knowledge of R and dplyr.

Solution: add a wrapper function for each plot that allows the user to create sensible plots with minimal number of arguments and no filtering needed on their side. After suggestion of @AlexAxthelm - feel free to add more context/requirements.

[MonikaFu]

Closed in #359 and #364