Documentation improvements - TO DO list

[CeresBarros]

To do:

• convert all @import to @importFrom
• add obj classes to all @param and @return
• add missing pkg/function imports
• add documentation to @noRd functions (maybe; see Documentation for @noRd functions  #110)
• move all function definitions that are inside other functions to non-exported functions #127
• add examples where they are missing and needed
• make code prettier (e.g. spacing)
• try to use @template where possible
• group documentation of thematically similar functions

[CeresBarros]

6aefa90 added more examples

[CeresBarros]

marking this issue done and reopening another dedicated to documentation examples