Honor MAX_DISPLAY_ENTRIES when inspecting variables (#629)

* Make sure we honor MAX_DISPLAY_ENTRIES for lists

* Honor `MAX_DISPLAY_ENTRIES` for atomic vectors.

* Honor `MAX_DISPLAY_ENTRIES` when inspecting matrix

* Make sure we truncate display value and names when necessary.

* Make sure we correctly truncate the matrix columns too

* Make sure environments are also limited.

* Make sure we truncate the display value in the scalar atomic case.

* Handle matrix with large character elements

* Fix performance! .join() is not lazy

* Use `env.bind()` , make it clear

* Also use environment wrapper here

* Use env method for empty environment