v0.5.9

Added:

• Add Alt . keybinding to bashisms-xontrib to insert last argument of
  previous command into current buffer

Fixed:

• Fix crash when openSSH version of bash is on PATH on Windows.

• Added missing ensurers to make sure that bool env_vars are bools and
  int env_vars are integers:

  • DIRSTACK_SIZE
  • EXPAND_ENV_VARS
  • PUSHD_MINUS
  • PUSHD_SILENT
  • SUGGEST_COMMANDS
  • SUGGEST_MAX_NUM
  • SUGGEST_THRESHOLD