Export class definitions (#6540)

* include `class_guide` for completeness

* structure indicators

* export & write documentation

* roxygenate

* All constructors have `...` as argument.

* warn about `...` when not empty

* simplify test

* bump version per @schloerke's request

* mark docpage as internal

* more strategic placement of `...`, thanks for the suggestion @schloerke!

* add default args

Author: teunbrand

DESCRIPTION

@@ -1,6 +1,6 @@
 Package: ggplot2
 Title: Create Elegant Data Visualisations Using the Grammar of Graphics
-Version: 3.5.2.9001
+Version: 3.5.2.9002
 Authors@R: c(
     person("Hadley", "Wickham", , "hadley@posit.co", role = "aut",
            comment = c(ORCID = "0000-0003-4757-117X")),

NAMESPACE

@@ -295,11 +295,26 @@ export(borders)
 export(build_ggplot)
 export(calc_element)
 export(check_device)
+export(class_S3_gg)
+export(class_coord)
+export(class_derive)
+export(class_facet)
+export(class_gg)
 export(class_ggplot)
 export(class_ggplot_built)
+export(class_ggproto)
+export(class_guide)
+export(class_guides)
 export(class_labels)
+export(class_layer)
+export(class_layout)
 export(class_mapping)
+export(class_rel)
+export(class_scale)
+export(class_scales_list)
 export(class_theme)
+export(class_waiver)
+export(class_zero_grob)
 export(combine_vars)
 export(complete_theme)
 export(continuous_scale)