PR# 4124 HASH_TABLE.clear_all does not do what the header comment says

The header comment of HASH_TABLE.clear_all says:

  "Reset all items to default values"

This is indeed what routines with the same name do in EiffelBase (e.g. ARRAY.clear_all). But what HASH_TABLE.clear_all does is actually removing all items
from the container, also known as `wipe_out' everywhere else in EiffelBase (e.g. LIST.wipe_out). I wonder why HASH_TABLE.clear_all is not named `wipe_out'. After all, name consistency is one of the strong points of EiffelBase.

(Another similar inconsistency is STRING.clear_all/wipe_out.)