Add tab-completion support to the interactive REPL by introducing a new `Meta.getModuleVariables` foreign method that returns all top-level variable names from a given module. The REPL's `run()` method now handles the tab key to append completions, and the `refreshLine` method accepts a boolean parameter to control whether completion hints are shown. Also fix the Ctrl-D exit logic (inverted condition) and remove the unused `EscapeBracket` class.
Bob Nystrom
69498a4893