Added is_debug method to settings
Added language and variant name when the debug is active
Code cleanup
Added limited multiprocess play
Added stop method
Code cleanup
Implemented stop and play for the eSpeak engine
Code cleanup
Moved Settings object from MainWindows to Backend object
Added debug messages
Added debug_line method to Settings object
Code cleanup
New voice engine for MBROLA
Allow each engine to be enabled or disabled
Their status will be automatically saved and restored
Added tooltips with languages and variants count
Updated gitignore