explorer_body: Explorer Body
In DavidBarke/shinyExplorer: Explorer and Contextmenu for Shiny apps

You usually don't want to call this module explicitly.

explorer_body_ui(id)

explorer_body(
  input,
  output,
  session,
  .values,
  .children_r,
  .root_node_r,
  .explorer_classes,
  .explorer_class_returns,
  .explorer_rvs,
  explorer_addable_r,
  explorer_visible_r,
  .label_list
)

`id`	Module id.
`input, output, session`	Called by `callModule`.
`.values`	The `.values` list.
`.children_r`	`reactive` containing the child nodes of the current node.
`.root_node_r`	A `reactive` returning an object of class `ExplorerNode`. This needs not necessarily to be the root node of an object of class `ExplorerTree`.
`.explorer_classes`	A `list` of objects of class `ExplorerClass`.
`.explorer_rvs`	`ReactiveValues`.
`.label_list`	A `list` created with `label_explorer` containing labels for all buttons used inside the explorer module.

#' .explorer_rvs must provide the following elements:

`current_node`	`ExplorerNode`, which is currently selected in `explorer`.
`contextmenued_node`	`ExplorerNode`, which has been last contextmenued.
`module_ids`	`List` with one entry per unique explorer class.