Delete ~IMUFileWriter as it is redondant with ~SplitIMUWavFilter

src/filewriter.h

@@ -237,7 +237,6 @@ public:
     void DecodeMessage(unsigned char c);
 
     IMUFileWriter(std::string &filename_template, size_t num_channels, size_t sample_rate, size_t depth, size_t timestamp);
-    ~IMUFileWriter();
     void write(uint8_t *samples, size_t num_samples, uint8_t *imu_data) override;
     size_t get_last_timestamp();
 };