signal filtration methods not implemented

i'm going to need somebody else to give me the math -- it doesn't look
like anything's actually finished for this in the original code.
implemented basic maximum calculations in drop

not doing any windowing of data (so not accounting for any second bounces
or anything like that).

currently taking the absolute value of the xyz accelerations but not the
xyz loads. that may be the wrong decision -- need to look at the data
output more closely to figure that out.