A filtering script

```sh
$ filter.py -m=ab data/weights -a=.4 -b=0 -i=160 -d=1 -r
Testing on N=12
Using alpha=0.4000, beta=0.0000
Initial estimate of 160.0000, accelerating 1.0000 per time unit
  Actual:   Est.:
  ========  ========
  158.0000  159.8000
  164.2000  162.1600
  160.3000  162.0160
  159.9000  161.7696
  162.1000  162.5018
  164.6000  163.9411
  169.6000  166.8046
  167.4000  167.6428
  166.4000  167.7457
  171.0000  169.6474
  171.2000  170.8684
  172.6000  172.1611
```