Release 3.15.0

Changelog:

Features/Changes:

• Add cartesian force/torque Vector3f members to command and feedback messages
• Add drivetrain status and motor hall state to feedback messages
• Update C API dependency to 2.22.0 to support additional feedback types listed above

Bugfixes:

• Null characters in UserSettings bytes payloads no longer terminate the string early (from C API update 2.22.0)
• Reduced warnings and comment typos. Public interface changes are limited to:
  • changing int to size_t for Group and LogFile size() functions
  • changing float to double for Arm::enabledRatio() and Arm::rampTime()