Encapsulate fgeo.tool

[maurolepore]

RE #76.

In module

• Do:

• ensure to export the minimum possible
• ensure to not document internal functions by using #' @noRd.
• don't use #' @keywords internal if using @nord.
• pay particular attention to generics and methods.

In fgeo

• Create R/module-reexport.R

For each function

• Reexport function and documentation
• Use @family to create a concept that can be included in fgeo's website