BMFHeading constructor
- {double magneticHeading,
 - double trueHeading,
 - double headingAccuracy,
 - double x,
 - double y,
 - double z,
 - String timestamp}
 
Implementation
BMFHeading(
    {this.magneticHeading,
    this.trueHeading,
    this.headingAccuracy,
    this.x,
    this.y,
    this.z,
    this.timestamp});