The ESS accelerometer code has gotten very complicated and I would like to simplify it as follows:

• Eliminate the min_frequency config parameter and always use 0. This will fix (make constant) the number of raw samples that go into one accelerometerPSD message. To compute fancier PSDs, get raw data from the EFD.
• Always publish the raw data (accelerometer topic): eliminate the config switch that allows turning this off.
• Update the XML so that the raw accelerometer topic has the correct length arrays so that there can be one accelerometer message for each accelerometerPSD message.