9.1.0

Added

• Better UI messages for breakpoint management.

Fixed

• where command failing on instance_exec block stack frames.
• restart command crashing in certain cases because of a missing require 'English' (#321, @akaneko3).
• restart command crashing when debugged script is not executable or has no shebang (#321, @akaneko3).

Removed

• Ruby 2.0 and Ruby 2.1 official & unofficial support. Byebug no longer installs
  on these platforms.