performance: probably unnecessary array copies in _compute_all method from EKF class

Those copies can be quite inneficient and it looks useless:

Lines 1107 to 1108 in 761ff0e

    
           self.gyr = np.copy(self.gyr) 
        
           self.acc = np.copy(self.acc)

Same for magnetometer here:

Line 1117 in 761ff0e

self.mag = np.copy(self.mag)

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