v1.9.1

• Addresses display issues in tmux panes where background colors bled through
  due to changed character rendering
• Updated ps method to return an empty hash {} instead of raising an error
  when PerformanceStatistics key doesn't exist in IORegistry
• Added exist? method to the Hackmac module to check if plist data is
  loaded, returning @plist instance variable or nil if no data is available
• Ensured the returned value is always a hash in the ps method
• Modified ps method to handle nil values from ps[metric] by defaulting to
  0 to prevent potential errors when metric data is missing from the
  process snapshot