Added support for the myBraille family of Help Tech Braille displays.

[FelixGruetzmacher]

Link to issue number:

Not applicable.

Summary of the issue:

The Help Tech myBraille models should be supported.

Description of user facing changes:

The myBraille family of Help Tech Braille devices are now fully supported via USB and Bluetooth, including automatic detection.

Description of developer facing changes:

The driver was changed accordingly. No API changes.

Description of development approach:

The device ID bytes for the four new models were added. A common superclass for them was introduced and then specialized into four model-specific classes. A common factory was considered but dismissed as the features of the different models may diverge in the future.

Testing strategy:

Functionality was tested with demo units of the different myBraille models.

Known issues with pull request:

None.

Code Review Checklist:

• Documentation:
  • Change log entry
  • User Documentation
  • Developer / Technical Documentation
  • Context sensitive help for GUI changes
• Testing:
  • Unit tests
  • System (end to end) tests
  • Manual testing
• UX of all users considered:
  • Speech
  • Braille
  • Low Vision
  • Different web browsers
  • Localization in other languages / culture than English
• API is compatible with existing add-ons.
• Security precautions taken.