Backspace/Delete allows modifying REPL history

[ivankozik]

Backspace and Delete handling is broken in several cases. The characters [ and ] below are used to indicate the beginning and end of the text selection, respectively. The character | is used to indicate the cursor position.

In this state, pressing Backspace or Delete causes the prompt text to be deleted:

[user=> ]|"xyz"

the same happens in this state:

[user=> "xy]|z"

JConsole should not permit deleting the prompt text.

In this state, pressing Backspace or Delete does not delete anything:

us|[er=> "xyz"]

JConsole should instead delete the input text without deleting any of the prompt text.